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UNITED STATES NATIONAL MUSEUM BULLETIN 247
Fossil Marine Mammals |
From the Miocene —
Calvert Formation
of Maryland and Virginia
REMINGTON KELLOGG
SMITHSONIAN INSTITUTION PRESS
CITY OF WASHINGTON
1969
Publications of the United States National Museum
The scientific publications of the United States National Museum include two
series, Proceedings of the United States National Museum and United States National
Museum Bulletin.
In these series are published original articles and monographs dealing with the
collections and work of the Museum and setting forth newly acquired facts in the
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publication are distributed to libraries and scientific organizations and to specialists
and others interested in the various subjects.
The Proceedings, begun in 1878, are intended for the publication, in separate
form, of shorter papers. These are gathered in volumes, octavo in size, with the
publication date of each paper recorded in the table of contents of the volume.
In the Bulletin series, the first of which was issued in 1875, appear longer, separate
publications consisting of monographs (occasionally in several parts) and volumes
in which are collected works on related subjects. Bulletins are either octavo or quarto
in size, depending on the needs of the presentation. Since 1902, papers relating to the
botanical collections of the Museum have been published in the Bulletin series under
the heading Contributions from the United States National Herbarium.
This work forms number 247 of the Bulletin series.
Frank A. TayLor
Director, United States National Museum
U.S. GOVERNMENT PRINTING OFFICE
WASHINGTON : 1969
CONTENTS
A new whalebone whale from the Miocene Calvert Formation
(Published 15 October 1965)
The Miocene Calvert Sperm Whale Orycterocetus. . . . . . ..
(Published 15 October 1965)
New Species of Extinct Miocene Sirenia ...........
(Published 28 November 1966)
A New Odontocete from the Calvert Miocene of Maryland . . .
(Published 28 November 1966)
Miocene Calvert Mysticetes Described by Cope. .......
(Published 12 June 1968)
A Hitherto Unrecognized Calvert Cetothere .........
(Published 12 June 1968)
A Sharp-nosed Cetothere from the Miocene Calvert. . ... .
(Published 12 June 1968)
Supplement to Description of Parietobalaena palmeri. . . ... .
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UNITED STATES NATIONAL MUSEUM BULLETIN 247
FOSSIL MARINE MAMMALS
From the Miocene Calvert Formation
Of Maryland and Virginia
Parts 1 and 2
REMINGTON KELLOGG
Research Assoctate, Smithsonian Institution
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SMITHSONIAN INSTITUTION +¢ WASHINGTON, D.C. + 1965
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1. A New Whalebone Whale From The
Miocene Calvert Formation
2. The Miocene Calvert Sperm Whale
Orycterocetus
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1. A New Whalebone Whale From The
Miocene Calvert Formation
OR NEARLY 100 YEARS beach-worn vertebrae and
portions of mandibles comprised the basis for descrip-
tions of many of the mysticetes derived from the Miocene
Calvert formation of Maryland and Virginia. Precise
localities for the fossil cetaceans were not included by Cope
in his descriptions of specimens received from James T.
Thomas of Charles County, Md., and since then preserved
in the Academy of Natural Sciences of Philadelphia (ANSP).
The mysticetes described by Cope in 1895 and 1896 were
based on incomplete mandibles and crania belonging to
collections assembled for the Woman’s College, Baltimore,
the Johns Hopkins University, Baltimore, and the Maryland
Geological Survey, Annapolis; and several of them, in
the passage of time, had become disassociated from original
locality information. Critical review and comparison of
these type specimens with more complete materials since
acquired has provided a better understanding of these
extinct mysticetes. A rather comprehensive assemblage
of the fossil mysticetes present in the Chesapeake em-
bayment during the interval in which the Calvert formation
was deposited were available for the present review, the
object of which is to describe one of the larger Calvert
species.
It is, however, necessary to make some disposition of the
possible applicability of the specific names Cope proposed
for mysticete fossil remains from the Miocene Calvert
formation to the skeletal remains described in the present
study.
Ten of the names proposed for rather inadequate cetacean
skeletal remains, which were derived from the Miocene
formations of Maryland and Virginia, are now thought
to have been applied to mysticetes. Cope based his
descriptions of four of these (Eschrichtius leptocentrus, 1867;
Eschrichtius pusillus, 1868; Delphinapterus tyrannus, 1868;
and Megaptera expansa, 1868) wholly or in a large part on
vertebrae, three chiefly on portions of mandibles (Esch-
richtius cephalus, 1867; Mesocetus siphunculus, 1895; and Ulias
moratus, 1895), and one on an incomplete cranium
(Metopocetus durinasus, 1896). The type of Leidy’s Balaena
prisca, 1852, is restricted to the fragment of a mandible,
since the caudal vertebra obviously belonged to another
cetacean. A cranium was the basis for Parietobalaena
palmeri Kellogg, 1924. The configuration and relations
of the bones comprising the rostral and occipital portions
of the type skulls of MM. durinasus and P. palmeri are quite
unlike the skull of the cetothere hereinafter described.
As regards the mandible, obvious structural features of
the type mandibles of E. cephalus, U. moratus, B. priscus
and M. siphunculus readily eliminate these species from
further consideration.
An imperfectly preserved cervical vertebra, which was
obtained in eastern Virginia, was designated as the type
(ANSP 12693) of schrichiius leptocentrus Cope. This
vertebra is now regarded as having come from the neck of
a balaenopterine whale and this allocation seems also io be
in accordance with the considerations which led Cope to
employ the generic name Eschrichtius.
Cope originally in 1868 based Megaptera expansa (ANSP
12769), on numerous vertebrae from the Thomas collection,
several from the Nomini Cliffs, Westmoreland Co., Va.
(presented to the Academy by Oliver N. Bryan of [Marshall
Hall], Charles County, Md.), and some in the Academy’s
Museum from Virginia. He did not describe the cervicals
which he remarked were not in his possession at that time,
but he gave some particulars and measurements of one
dorsal and one lumbar vertebra. The epiphyses of both of
these vertebrae are completely ankylosed to the centrum.
The dorsal, the lumbar and other vertebrae included in the
type series by Cope conform in general characteristics to the
vertebrae of one of the smaller Miocene Calvert cetotheres.
Cope in his description of the centra of the type series of
M. expansa seems to attribute some importance to the dorsal
flattening and transverse subcordate outline of their articular
faces or ends. The centra of the anterior and middle dorsal
1
2 UNITED STATES NATIONAL MUSEUM BULLETIN 247
vertebrae of at least three of the Miocene Calvert cetotheres
exhibit this shape. The seventh dorsals of the Miocene
Anversian Mesocetus longirostris (Van Beneden, 1886, pl. 40,
fig. 1) and Mesocetus pinguis (Van Beneden, 1886, pl. 48,
fig. 1) of the Antwerp basin, Belgium, for example, both
exhibit this configuration and the first mentioned species
agrees closely in dimensions with those of M. expansa.
In the original description Cope (1868, p. 190) stated
that Delphinapterus tyrannus was represented in the collection
by one dorsal and three lumbars, but their epiphyses were
unfortunately lost, and that three of these vertebrae belonged
to one individual. The length of the centrum, including an
estimate for the missing epiphyses, of one of these lumbars
was given by Cope as 3 inches (76.2 mm.). The vertebrae
now labeled as the type series (11252) in the Academy of
Natural Sciences of Philadelphia comprise four lumbar and
one caudal vertebrae, the centra of which measure in length
57, 71, 70, 89, and 84 mm., respectively. The caudal has
both epiphyses attached to the centrum. Cope may have
included this caudal in the series at a later date inasmuch
as the epiphyses are ankylosed to the centrum. One of the
four lumbars may have been regardedasa dorsal. Although
this individual was immature these lumbar vertebrae,
characterized in part by short and rather narrow transverse
processes, unquestionably belonged to a somewhat different
and smaller mysticete than the large species hereinafter
described.
“Many vertebrae, of which one dorsal, six of the lumbars,
and one caudal may serve as types’ (Cope (1868, pp.
191-192)) were associated in the same description of
Eschrichtius pusillus with the mandible of a much smaller
cetothere. The published measurements were: dorsal ver-
tebra — centrum length 125 mm., width 108 mm.; lumbar
vertebra — centrum length 125 mm., width 106 mm.;
caudal vertebra — centrum length 101.6 mm., width
101.6 mm. The articular end of the dorsal is described as
a depressed oval which normally would correspond with a
vertebra at the posterior end of that series. Aside from the
usual longitudinal ventral keel, the lumbar is described as
having vascular foramina ‘“‘so small as not to be noticeable.”
On the caudal vertebra the pair of ventral keels (haemapo-
physes) bounding the haemal groove are described as
“very slight,” and the transverse processes not perforated.
These processes have been broken off and lost. Non-
perforated transverse processes and the complete enclosure
of the neural canal by an arch extending three-fourths the
Jength of the centrum place this caudal in the anterior
half of this series. An examination of the series of vertebrae
(ANSP 12769) labeled as types reveals that all are beach
worn specimens generally devoid of all processes of the
centrum. The dimensions, proportions and configurations
of the best preserved centra in this type series of Eschrichtius
pusillus agree most closely with a Calvert cetothere (USNM
PART 1
15885) whose lumbar vertebrae possess rather short and
broad transverse processes and a broad neural spine of
moderate height. The ventral surface of the centrum,
presumably designated as the dorsal by Cope, is eroded to
such an extent that the original outer surface is no longer
visible and no trace of a ventral keel is observable.
Some allowance should be made in evaluating the impor-
tance of differences in the measurements of mysticete
vertebrae for purposes of identification. Growth seemingly
continues at a decreasing rate as long as inter-cartilaginous
discs persist between the centra of the vertebra and its
epiphyses. When this process of ossification of the vertebral
column (which proceeds forward from the terminal caudal
and backward from the axis toward the middle of the
vertebral column), is completed, physical maturity is
attained and growth is thought to have ceased. Neverthe-
less, physical maturity is attained by females of the Recent
blue whale at lengths varying from 81 to 94 feet, and yet
the largest definitely recorded immature blue whale was
93 feet. Blue whales measuring about 100 feet have been
encountered as well as undersized individuals. It may be
presumed from the examination of the vertebrae of a
number of individuals representing at least three species of
Miocene Calvert mysticetes that similar conditions of
growth and attainment of physical maturity prevailed at
least during this period of their geological history.
In the present state of our knowledge the vertebral
columns of the Miocene Calvert mysticetes seem to be
most readily distinguished from one another by structural
features of their lumbar vertebrae. For example the
lumbar vertebrae of the large cetothere described in the
present study possess high broad neural spines and wide
elongated transverse processes. The lumbar vertebrae of
another cetothere of medium size possess broad, but
slightly shorter neural spines and less elongated spatulate
transverse processes. The lumbar vertebrae of the smallest
Calvert cetothere possess narrower transverse processes and
rather slender neural spines.
Winge (1910) and True (1912) have commented on the
characters ascribed by Cope to his genera Cephalotropis,
Metopoceius, Rhegnopsis, Siphonocetus, Tretulias and Ulias,
the genotype specimens of which were derived from the
Miocene Chesapeake series of Maryland and Virginia.
Since the time when these comments were published con-
siderably more new and adequately preserved skeletal
materials have been accumulated. These materials do not
substantiate all of the conclusions set forth by these investi-
gators, especially the validity of allocations of these genera
to Cetotherium and Plesiocetus. Discussion of the validity of
these genera will be included in forthcoming revisions
of their mysticete skeletal remains and further comment
will be deferred until then.
A NEW WHALEBONE WHALE 3
Abel (1938, p. 15) did not accept the distinction between
skulls of Cetotheriidae and Balaenopteridae proposed by
Miller (1923, p. 21) and Kellogg (1931, pp. 305-306).
One quite obvious modification observable in cranial re-
modeling among genera assigned to these two families,
respectively, was described as follows:
As viewed from the dorsal aspect the supraorbital process
of the frontal is abruptly depressed at the base to a level
below the dorsal surface of the interorbital region of the
balaenopterine whale skull. Conversely, the supraorbital
process of the frontal slopes gradually downward and out-
ward from the level of the dorsal surface of the interorbital
region of the cetothere skull. Abel contends that such a
distinction is not valid since this condition represents a
gradual modification of the skulls of the more ancient and
the more recent Balaenopteridae. Abel mentions also the
skull of Rhachianectes [= Eschrichtius], the sole living repre-
sentative of another family (Rhachianectidae = Eschrichti-
idae), which has a gradually sloping supraorbital process.
As yet no fossil mysticete skull has been described which
exhibits transitional stages in this alteration of the basal
portion of the supraorbital process of the frontal. It does
not necessarily follow, however, that such stages were non-
existent. Irrespective of differences of opinion as regards
the functional significance of this balaenopterine cranial
remodeling, this modification does provide a readily ob-
servable structural feature for the family allocation of
similarly constructed genera.
The skeletal length of the largest of the three individuals
represented in part by vertebrae and hereinafter described
is estimated as at least 22 feet. From other Miocene Calvert
mysticetes this cetothere is characterized chiefly by having
a scapula that lacks an acromion process, but possesses a
rather wide prescapular fossa. Elongated transverse proc-
esses and a high, broad neural spine distinguish the lumbar
vertebrae from those of coexistent species. The skull
measures slightly more than six feet in length, and its
mandibles are massive.
Cetothere genera most frequently have been distinguished
from one another by the particular combination of structural
cranial! details and less often by only one differing feature.
PELOCETUS, new genus
Type Species: Pélocetus calvertensis, new species.
Diagnosis: Apex of supraoccipital shield thrust forward
slightly beyond level of anterior ends of zygomatic proc-
esses; elongated nasals located in part anterior to level
of preorbital angles of supraorbital processes of frontals;
strong forward overthrust has carried anterior borders of
parietals to median interorbital region, overriding frontals,
but not extending forward to level of posterior ends of
median rostral elements (ascending processes of maxil-
laries, premaxillaries and nasals); backward thrust of
rostrum limited, median rostral elements (ascending
processes of maxillaries, premaxillaries and nasals) not
carried backward beyond level of middle of orbit; ex-
posure of frontals in median interorbital region reduced
to a narrow strip; a thin temporal crest on each supra-
orbital process; a short, pinched-in intertemporal con-
striction formed by opposite parietals meeting on midline;
wide temporal fossae; slender, bowed outward zygomatic
processes; alisphenoid present in temporal wall of cranium;
rostrum broad, sides nearly parallel on basal half and then
rather strongly curved to distal end and equivalent to
68 percent of total length of skull; narial fossae elongated;
palatines elongated, diverging posteriorly; lateral pro-
tuberances of basioccipital massive, larger than pterygoid
fossae; posterior process of periotic elongated and expanded
distally; horizontal ramus of mandible relatively deep,
and thick, the condyle large and convex in all directions;
articular facet for capitulum of following rib situated on
first to eighth dorsal vertebrae, inclusive, below level of
floor of neural canal and adjacent to edge of posterior
face of centrum; lumbar vertebrae have relatively broad
and high neural spines, elongated transverse processes and
thin lamina-like metapophyses; second to ninth ribs,
inclusive, have capitulum at end of elongated neck;
scapula fan-shaped, exhibiting no vestige of acromion
although possessing a coracoid process, and having pre-
scapular fossa relatively broad and flat; humerus has
anterior or radial face of shaft markedly rugose; distal
epiphyses of radius and ulna detached and not completely
ossified.
PELOCETUS CALVERTENSIS, new species
Type Specimen: USNM 11976. Skull (essentially com-
plete except for both lachrymals and right jugal); left
jugal detached; both tympanic bullae and periotics; both
mandibles, somewhat damaged distally; six cervical
vertebrae; nine dorsal vertebrae; eight Jumbar vertebrae;
two caudal vertebrae; left scapula essentially complete;
right scapula, basal and anterior borders preserved; right
and left humeri; right and left radii; distal portion of left
ulna; eleven carpals; nine metacarpals; nine phalanges;
fourteen ribs, more or less complete; united basihyal and
thyrohyals; right stylohyal, nearly complete; left stylohyal,
inner portion only. Collectors, A. Lincoln Dryden, Jr.,
Willard Berry, William L. Jones, Arthur J. Poole, and
Remington Kellogg; August 22-27, 1929, and August
14-20, 1931.
Horizon and Locality: Three feet below top of Zone 13
at base of cliff about 665 yards north of old wharf at end of
road at Governor Run, Calvert County, Maryland.
Calvert formation, upper Miocene.
4 UNITED STATES NATIONAL MUSEUM BULLETIN 247
Referred Specimens: Four, as follows: (1) USNM 14693:
anterior end of right mandible, coll. Charles W. Gilmore,
Ed. Mullins and Remington Kellogg, July 29, 1936;
in zone 13 on face of high cliff 24% miles south of Chesa-
peake Beach wharf, Calvert County, Md., Calvert for-
mation, middle Miocene. (2) USNM 21306: anterior
end of right mandible, coll. Charles L. Kimbell, July 9,
1949; in zone 17, red brown shell band about 40 feet above
beach level, 35 feet south of commencement of first cliff
south of Parker Creek, Calvert Co., Md. Choptank for-
mation, middle Miocene. (3) USNM 23058: four dorsal
vertebrae, seven lumbar vertebrae, six ribs and two rib
heads, three phalanges, coll. Robert E. Weems, September
1962; Stratford Cliffs, about 3.8 miles below mouth of
Pope’s Creek, about 200 feet west of second swamp below
(east of) “Big Meadows” in bluish sandy clay with vertical
seams about 3 feet above beach level, Westmoreland County,
Va., Calvert formation, middie Miocene. (4) USNM
23059: atlas, 3 dorsal vertebrae, 1 lumbar vertebra and
a detached neural spine, 5 caudal vetebrae, right scapula
(articular end), right ulna, 6 phalanges, 4 carpals, 16
ribs, right occipital condyle and right squamosal and
adjoining bones, 2 tympanic bullae, left periotic, 1 jugal,
coll. Robert E. Weems, August 1963; about 3.5 miles
below mouth of Pope’s Creek in Stratford Cliffs, about
100 feet beyond swamp below (east of) “‘Big Meadows,”
in blue marly clay with vertical seams about 4 feet above
beach level, Westmoreland Co., Va., Calvert formation,
middle Miocene.
Skull
This is the largest and best preserved cetothere skull
(USNM 11976; pl. 1) thus far collected in the Miocene
Calvert formation. Erosion or weathering removed the orig-
inal external osseous surface of the squamosals and of their
zygomatic processes as well as the surface on the posterior
portion of the parietals. The outer border of the right max-
illary on the rostrum and the anteroexternal portion of the
right supraorbital process of the frontal were damaged prior
to excavation. Both supraorbital processes were crushed and
cracked, seemingly by the pressure applied by superimposed
vertebral centra and limb bones.
This skull is characterized chiefly by absence of a pro-
nounced tapering of the rostrum, limited interdigitation by
backward thrust of rostral elements, strong forward thrust
of supraoccipital and the parietals, reduced exposure of the
frontals in median interorbital region, pinched-in inter-
temporal constriction, wide temporal fossae, elongated
dorsal narial fossa, slender zygomatic processes, and large
robust postglenoid processes.
DorsaL view.—When this skull (fig. 1) is examined from
a dorsal view, attention is directed to the large subtriangular
occipital shield whose pointed apex extends forward slightly
PART 1
beyond the level of the anterior ends of the zygomatic
processes, the forward overthrust of the parietals on the
frontals in the median interorbital region, outward bowed
zygomatic processes, the presence of a thin transverse crest
on each supraorbital process, elongated nasal bones, and
a broad rostrum.
For more than half of the length of the rostrum, the sides
are almost parallel proximally and then become rather
strongly curved to the distal end. The rostrum contributed
more than 68 percent of the total length of the skull. The
maxillaries are broad at the base of the rostrum, and are
relatively thin along their lateral borders. The dorsal
surface of each maxillary slopes gradually from the maxil-
lary-premaxillary suture to its outer edge. The dorsal
ascending process of each maxillary is quite short, although
it extends backward to the level of the posterior ends of the
premaxillaries and nasals. No abrupt indentation for an
antorbital notch is developed and the posteroexternal
portion of the maxillary immediately in contact with the
preorbital angle of the supraorbital process of the frontal is
reduced to a narrow platelike strip. Each maxillary was,
however, interlocked with the corresponding frontal even
though it does not overspread the supraorbital process.
Both maxillaries are pierced by five foramina, which are,
however, differently located in each.
On each side of the rostrum of a somewhat smaller ceto-
there skull (USNM 16783), regarded as belonging to a
different species with a strongly attenuated rostrum, a wide
incisure extends obliquely forward toward the maxillary-
premaxillary sutural contact commencing in front of the
antorbital notch, separating the triangular portion of the
maxillary behind it into a dorsal and ventral plate and thus
forming the walls of a broad cavity that extends backward
ventrally to the anteroventral edge of the supraorbital
process of the frontal. That this incisure is not a fortuitous
aberration is shown by a similar modification on the rostral
portions of the maxillaries of a second individual (USNM
16871) of the same species. A deep pitlike depression in
conjuction with the possible destruction of the dorsal plate
of the corresponding portion of each maxillary of this larger
skull may if this interpretation is correct be attributable to
a like structural modification. In view of the existing
uncertainties these depressions are not indicated on the text
illustration (fig. 1).
Anterior to the forward extension of the vomer, each
premaxillary curves downward and inward to meet its
opposite on the midline of the rostrum. The vomer pos-
teriorly and the premaxillaries anteriorly contribute the
floor and the sides of the longitudinal rostral gutter. Each
premaxillary attains its maximum width (105 mm.) at the
level of the anterior ends of the maxillaries, and projects
forward 140 mm. beyond the level of the anterior ends of
the latter. The slender facial or ascending process of each
FicurE 1.—Dorsal view of skull,
USNM 11976, of Pelocetus calverten-
sis, with restored borders of rostrum
and right supraorbital process.
Abbrs.: Al., alisphenoid; ant.n.,
antorbital notch; Bo., basioccipital;
C., occipital condyle; Ex.oc., exoc-
cipital; f.max., maxillary foramen;
f.ov., foramen ovale; h.pt., hamular
process of pterygoid; j.n., jugular
notch or incisure; |.pr., lateral or
descending process of basioccipital;
Max., maxilla; Na., nasal; o.c.,
optic canal; Pal., palatine; Par.,
parietal; pgl., postglenoid process;
Pmx., premaxilla; pr.p., posterior
process of periotic; Pt., pterygoid;
S.oc., supraoccipital; Ty., tympanic
bulla; V., vomer; zyg., zygomatic
process.
755—999— 65. 2
A NEW WHALEBONE WHALE 5
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;
6 UNITED STATES NATIONAL MUSEUM BULLETIN 247
premaxilary is lodged in a groove which parallels the
dorsointernal angle of the hinder end of the maxillary and
the external edge of the corresponding nasal and terminates
at the level of the posterior ends of these nasal bones. The
dorsal surface of each premaxillary in front of the dorsal
narial fossa is slightly convex transversely, but becomes
noticeably flattened toward the anterior end. The back-
ward thrust of the median portion of the rostrum has
carried the ascending processes of the maxillaries and pre-
maxillaries as well as the nasals backward almost to the
level of the center of the orbit.
The dorsal narial fossa is deep, elongate and rather
narrow, the maximum transverse diameter at a point 235
mm. in front of the anterior ends of the nasal bones being
135 mm. The maximum anteroposterior diameter of this
fossa is approximately 350 mm.
The long, slender nasal bones are wedged in between the
ascending processes of the opposite premaxillaries; their
posterior extremities are mortised into the frontals and
anteriorly they overhang the dorsal narial fossa. ‘The
anterior ends of both nasals are rounded.
The frontals are exposed for a very short interval (30
mm.) between the hinder ends of the backward overriding
rostral bones and the intertemporal constriction occupied
by the parietals. The frontals, which are excluded from
the vertex by the parietals, slope gradually downward from
the dorsal surface of the interorbital region toward the
orbital rim of their supraorbital processes. ‘The relatively
narrow anterior border of the dorsal surface of each supra-
orbital process is demarcated from the much broader,
downward and backward sloping hinder portion by a low
curved transverse crest. The preorbital angle of the supra-
orbital process of the frontal is in close contact with the
dorsoexternal end of the maxillary; the postorbital pro-
jection is extended backward and outward to contact the
anterior end of the zygomatic process. The orbital rim of
the supraorbital process of the frontal is quite thin and
arched.
The opposite parietals, which meet medially to constitute
the short intertemporal constriction, are overridden on their
edges above and behind by the large triangular supra-
occipital shield. Anteriorly the thin narrow plate of the
parietal, which overrides the base of the supraorbital
process, extends forward to within 30 mm. of the hinder
ends of the ascending processes of the maxillaries. Each
parietal bone is relatively broad dorsoventrally and is
situated below the level of the lambdoidal crest to which
it contributes the outer edge; it comprises the major portion
of the lateral wall of the braincase. Behind the level of the
supraorbital process, the lower edge of the parietal anteriorly
is suturally in contact with the dorsal edge of the alisphenoid
and, behind the latter, the sutural contact between the
parietal and the squamosal curves outward, then upward
PART 1
and backward to meet the supraoccipital on the lambdoidal
crest.
The squamosal comprises the posterolateral portion of the
skull; its anterior face, which constitutes the hinder wall of
the temporal fossa, curves backward and outward from the
pterygoid and then forward to the extremity of its zygomatic
process. The squamosal is markedly depressed dorso-
ventrally, forming an elongated trough which is bounded
behind and externally by the lambdoidal crest. An obvious
outward bulge of the cranial cavity is developed above and
below the sutural contact between the parietal and the
squamosal. The zygomatic process is relatively slender, and
is bent outward and forward, flattened on its internal face,
convex externally, and narrowed dorsally to form a longi-
tudinal crest which, however, is not continuous posteriorly
with the lambdoidal crest. Posteriorly, the dorsal surface
of each zygomatic process is excavated to form a fore-and-
aft concave depression whose function is not readily
apparent.
From a dorsal view the occipital condyles appear rela-
tively small. Except at their outer ends the exoccipitals
were concealed from a dorsal view by the overhanging
lambdoidal crest.
The transverse diameter of the triangular occipital shield
(445 mm.) at the level of the top of the foramen magnum
exceeds its greatest length (distance from dorsal rim of
foramen magnum to apex, 325 mm.). The forward thrust
of the hinder elements of the cranium has pushed the apex
of the supraoccipital shield to the level of the most advanced
portion of the hinder edge of the supraorbital process of the
frontal and slightly beyond the level of the anterior ends of
the zygomatic processes. The median portion of the tri-
angular occipital shield is deeply depressed below its lateral
crestlike edges.
PosTERIOR viEw.—The broad occipital shield (fig. 2)
which forms the posterior wall of the braincase, is consti-
tuted by the medially depressed supraoccipital and the large
anteroposteriorly thickened exoccipitals. Both lambdoidal
crests are well preserved and each curves upward and for-
ward to the acutely pointed apex of the shield.
The exoccipitals are relatively large massive bones, which
constitute the lateral wings of the occipital shield, and their
external argles project backward at least 50 mm. beyond
the level of the articular faces of the occipital condyles. The
occipital condyles are large and the foramen magnum
relatively small. The articular surfaces of these condyles
are convex from end to end and also from side to side.
They are separated ventrally by a deep narrow notch.
Anterior to the condyles on each side of the basicranium is
the lateral knoblike descending process of the basioccipital
which contributes the inner wall of the wide jugular incisure.
The outer wall of this incisure for the jugular leash is con-
tributed by the exoccipital.
A NEW WHALEBONE WHALE of
i tH f
us
Ficure 2.—Posterior view of skull, USNM 11976, of Pelocetus calvertensis. For abbreviations, see figure 1.
Each large postglenoid process projects ventrally approxi-
mately 110 mm. below the level of the ventral edge of the
exoccipitals. Although the braincase appears somewhat
depressed, there is no visible evidence of a ruptured cranial
wall in either temporal fossa, although the dorsal rim of the
foramen magnum is pushed downward a few millimeters.
LATERAL VIEW.—Lhe apex of the supraoccipital shield
forms the highest point in the dorsal profile, although it is
only slightly higher than the point where the opposite
transverse temporal crests on the supraorbital processes
converge medially (limiting the forward overthrust of the
parietals) and in front of the latter, the dorsal profile of the
median interorbital region and of the rostrum slopes
gradually forward and downward to the extremity of the
rostrum.
The rostrum is rather deep proximally at the level of the
anterior ends of the palatine bones and gradually decreases
in depth anteriorly. The outer edge of the maxillary is
quite thin throughout its length.
The orbital border of the supraorbital process is dorso-
ventrally compressed and arched in a fore-and-aft direction.
Its preorbital angle is bluntly rounded and is underridden
by the posteroexternal angle of the maxillary. The post-
orbital projection is slightly deeper dorsoventrally (33 mm.)
than the preorbital angle. The supraorbital process as a
whole slopes downward from the interorbital region to
the orbital rim, and the much broader hinder portion is
set off from the narrower anterior border by a low curved
temporal crest.
The attenuated zygomatic process of the squamosal is
deepened dorsoventrally and its ventral profile exhibits a
regular curvature. The dorsal profile of the zygomatic
process rises gradually behind its anterior end and merges
posteriorly beyond the hinder dorsal depression with the
outwardly overrolling lateral crest on the squamosal, which
in turn is continuous behind with the short forward extension
of the lambdoidal crest.
Viewed from the side, the thick postglenoid process pro-
jects downward and backward, its posterior face is flattened
and its extremity is bent backward. The squamosal as a
whole is rather large and constitutes a considerable portion
of the external construction of the braincase. It is strongly
depressed in front of the hinder portion of the lambdoidal
crest as well as internal to the low lateral crest which is
continuous anteriorly with the dorsal edge of the zygomatic
process. Posteriorly, the squamosal is broadly sutured to
the anterior surface of the corresponding exoccipital.
The more or less vertical parietal is concavely curved from
end to end and constitutes the major portion of the lateral
wall of the braincase. It meets the parietal from the op-
posite side of the cranium to form a short and very narrow
isthmus or intertemporal constriction which connects the
occipital portion of the skull with the facial or interorbital
portion. The dorsal and hinder edges of the parietal form
a continuous curve, which is overlain by the lateral edge of
the supraoccipital shield, the apex of which extends forward
slightly beyond the level of the anterior ends of the zygo-
matic processes.
The occipital condyles are not visible when the skull is
viewed from the side. The ventral profile of the maxillaries
in the interval where they are overlain by the palatine
bones displays a gradual slope in a fore-and-aft direction
when viewed from the side.
The alisphenoid appears on the temporal wall of the
braincase as an irregularly shaped element and is located
behind the base of the posterointernal angle of the supra-
orbital process, but above the pterygoid. The exposed
outer end of the alisphenoid is somewhat elongated, the
8 UNITED STATES NATIONAL MUSEUM BULLETIN 247
greater length being in the anteroposterior direction. In
the temporal fossa, the alisphenoid is bounded dorsally and
anteriorly by the parietal, and ventrally by the pterygoid.
The alisphenoid has no contact posteriorly with the squa-
mosal (See Muller, 1954).
VENTRAL VIEW.—The ventral surface of this skull (pl. 2)
is fairly well preserved with the exception of portions of the
posterior region of each maxillary. During the past
thirty years the ventral surface of each maxillary has
deteriorated to a varying extent; as a result of crushing the
opposite palatines and maxillaries had spread apart along
the median longitudinal axis, exposing portions of the
ventral ridge of the trough of the vomer.
The horizontally widened maxillaries comprise the major
portion of the palatal surface of the skull (fig. 3). In
front of the supraorbital process of the frontal the palatal
surface of each maxillary is depressed, concavely curved
from side to side. Anterior to the palatine bones, a strong
tendency toward flattening on the outer portion is exhibited
by the maxillary, but throughout its length this bone
exhibits an upward convex curvature where it abuts
against the ventral surface of the trough of the vomer.
The ventral surface of the maxillary is also engraved with
a series of shallow, narrow and slightly curved grooves
which extend forward in an oblique direction from their
origin near the midline toward the outer margin of this
bone. These grooves on the posterior portion of the
maxillary in front of the level of the anterior ends of the
palatines are quite short and are bent more strongly
obliquely outward. The ligamentary tissues as well as
the blades of baleen which are attached to the roof of the
mouth in Recent mysticetes are supplied in these vascular
grooves. The thin posterior platelike border of each
maxillary is thrust backward on the ventral face of the
supraorbital process of the frontal almost to the edge of
the broad channel for the optic nerve.
The inner edges of the maxillaries commence to diverge
on the ventral aspect of the rostrum 365 mm. behind the
extremity of the right maxillary and 980 mm. in front of
the anterior edge of the right palatine. The right maxillary
terminates at a point 1340 mm. in front of the anterior end
of the left palatine. The distance from the anterior end
of the right maxillary to the anterior edge of the optic
canal at the base of the right supraorbital process is 1465
mm.
Between the anterior end of the vomer and the point of
divergence of the premaxillaries toward the end of the
rostrum, the premaxillaries meet ventrally along the
median longitudinal axis of the rostrum to constitute a
complete floor for the distal portion of the dorsal narial
gutter.
Commencing at a point 380 mm. in front of the anterior
edge of the right palatine, the inner edges of the maxillaries
PART 1
are spread apart slightly, exposing the ventral keel of the
vomer. At a point 480 mm. in front of the posterior edge
of the horizontal vaginal plate, the vomer develops a wide,
flattened ventral exposure, which extends backward at
almost the same horizontal level for a distance of 395 mm.
and then diminishes in height rather rapidly toward its
posterior edge. The trough of the vomer is widest near the
the level of the anterior ends of the palatines. The median
partition between the paired internal choanae is con-
stituted by the vomer. The hinder horizontally expanded
thin plate of the vomer is applied to the ventral surface of
the basisphenoid and overrides the anterior border of the
basioccipital and, in front of the former, it also envelops
the ventral and lateral surfaces of the alisphenoid. Ex-
ternally this horizontally expanded plate of the vomer is
suturally united with the vaginal process of the corre-
sponding pterygoid along each lateral margin.
The palatines are similar to those of the Modelo cetothere,
Mixocetus elysius (Kellogg, 1934) in that they constitute the
lower boundary of the optic foramen and extend backward
beyond the latter. The anterior end of each palatine is
obliquely truncated and is suturally united with the
posterointernal angle of the corresponding maxillary as well
as applied to the ventral face of the troughlike vomer.
Laterally for a distance of 150 to 160 mm. each palatine is
also mortised into the internal border of the hinder portion
of the corresponding maxillary. The hinder end of each
palatine is suturally united with the anterior edge of the
corresponding pterygoid. The anteroposterior diameter
ofthe palatine equals 16 percent of the total length of the skull.
The distally expanded supraorbital processes of the
frontals are extended outward almost to the level of the
posteroexternal angles of the maxillaries. The channel
for the optic nerve commences at the optic foramen and
curves transversely across the ventral surface of the supra-
orbital process of the frontal, becoming noticeably wider
toward the orbital rim of this process. Near its origin this
channel for the optic nerve is restricted to the hinder face
of the supraorbital process for a distance of about 90 mm.
and then twists downward until it is located wholly on the
ventral surface of the supraorbital process. In width, this
channel increases from a minimum diameter of 15 mm.
near its origin to a maximum of 110 mm. at the orbital rim
of this process. This optic channel is bounded by a high
curved osseous crest which at its origin constitutes the
ventral wall of the canal and then follows the hinder margin
of the supraorbital process to constitute the posterior
boundary for this channel. The anterior boundary is
formed by a high crest which is continued outward to the
orbital rim of this process.
The basioccipital viewed from the ventral side is a
rectangular shaped bone, with its long axis transverse to
the longitudinal axis of the skull. The basioccipital is
A NEW WHALEBONE WHALE
Figure 3.—Ventral view of skull,
-USNM 11976, of Pelocetus calverten-
sis, with restored borders of rostrum
and right supraorbital process. For
abbreviations, see figure 1.
cara GUE TOON 2A DRM
Max.
ant.n.
SOF pi»
10 UNITED STATES NATIONAL MUSEUM BULLETIN 247
ankylosed in front with the basisphenoid, the line of contact
being overspread by the horizontally expanded posterior
end of the vomer. On each side in front of and extending
externally beyond the level of the external face of the
occipital condyle is the very large, irregularly shaped
descending protuberance, which is obliquely flattened
internally on its anterior half. These opposite enlarged
lateral protuberances of the basioccipital greatly reduce
the transverse diameter of the median basicranial depression.
The transverse distance between the inner faces of these
protuberances does not exceed 75 mm. The somewhat
concavely curved external surfaces of these lateral protuber-
ances slope obliquely upward. The anterior end of each
lateral protuberance is fused with the vaginal process of the
corresponding pterygoid, and the line of contact nearly
coincides with the hinder end of the vomer. The ventral
surface of the vaginal process of the pterygoid is bent to
conform to the curvature of the corresponding surface of
the lateral protuberance. The basisphenoid is a flat
rectangular bone, the greater length being in the antero-
posterior direction. It is entirely concealed by the
horizontally expanded hinder plate of the vomer. This
bone is suturally united on each side with the vaginal
process of the pterygoid.
The vaginal process of the pterygoid is preserved in its
entirety on the right side and is slightly damaged on the left
side. This process is suturally united along its dorsal edge
with the outer edge of the basisphenoid. Along its dorso-
internal margin it meets or is ankylosed to the horizontally
expanded hinder plate of the vomer. The posterior end of
this vaginal process, as mentioned previously, is fused with
the anterior end of the lateral protuberance of the basioc-
cipital. These vaginal processes of the opposite pterygoids
take part in the formation of the lower boundaries of the
internal choanae and, in conjunction with the lateral pro-
tuberances of the basioccipital bound the median region of
the basicranium.
The hamular processes of the pterygoids curve backward
below and internal to the pterygoid fossa. A narrow strip
of the pterygoid is exposed between the hinder end of the
palatine and the bifurcated anterior end of the squamosal
which incloses the foramen ovale. The pterygoid extends
upward on the inner wall of the temporal fossa to meet the
lower edge of the alisphenoid. Dorsally and posteriorly
behind the alisphenoid, the pterygoid meets the parietal edge
to edge. The outer portion of the pterygoid extends for-
ward and is suturally united along its entire anterior edge
with the palatine, although the posterointernal angle of the
palatine is free. Behind the level of the origin of the channel
for the optic nerve on the supraorbital process of the frontal,
the lateral (external) wall of the narial passage is formed by
the pterygoid. The mandibular branch of the trigeminal
PART 1
nerve follows the broad curved groove on the ventral surface
of the pterygoid on the roof of the pterygoid fossa.
The rather small pterygoid fossa (Ridewood, 1922, p. 260)
or sinus is bounded internally by the vaginal process of the
pterygoid anteriorly and anteroexternally by the downward
curvature of the thickened anterior and external borders of
the pterygoid and posteroexternally by the short and rather
narrow falciform process of the squamosal. The roof of this
air containing pterygoid fossa is constituted by the pterygoid
and ventrally it has no apparent osseous cover. The ptery-
goid fossa is not limited posteriorly by any bony plate or
process, but is continuous with the tympanoperiotic recess.
The rather large tympanoperiotic recess opens into the
interior of the cranium. This recess is bounded by the
squamosal and its falciform process externally, by the ptery-
goid anteriorly, by the lateral protuberance of the basioc-
cipital internally and by the exoccipital posteriorly.
The posterior lacerated foramen for the jugular leash is
represented by a broad notch or incisure which is located at
the posterointernal angle of the tympanoperiotic recess.
This notch is bounded by the lateral protuberance of the
basioccipital internally and by the exoccipital externally
and dorsally.
On this Calvert skull there is a groove leading through the
notch in the squamosal in front of the level of the sigmoid
process of the bulla and behind the anterior process of the
periotic, but in the same relative position as the well defined
foramen on the Astoria cetothere skull, Cophocetus oregonensis
(Packard and Kellogg, 1934, fig. 4).
On the ventral surface, the contact between the squamosal
and the exoccipital lies above the posterior process of the
periotic, and the latter is firmly wedged in between these
two bones. Between the posterior process of the periotic
and the base of the hinder face of the postglenoid process is
a curved transverse channel for the external auditory
meatus, which widens toward its external terminus. This
channel, which is directed at an oblique angle to the longi-
tudinal axis of the skull, originates at the inner edge of the
squamosal and extends outward to a limited extent on the
ventral surface of the posterior process of the periotic.
The elongated zygomatic process is attenuated from its
base toward the extremity and is bowed outward, its ex-
ternal profile viewed from below, exhibiting a convex cur-
vature from end to end. The postglenoid process projects
downward at least 110 mm. below the level of the corre-
sponding lateral protuberance of the basioccipital. This
postglenoid process is very robust, with its extremity com-
pressed anteroposteriorly and deflected backward, its
posterior face curved concavely and its external face con-
vex. ‘This process is also characterized by a more or less
flattened anterior face which slopes obliquely upward
from its extremity to the external concave glenoid facet for
articulation with the condyle of the mandible.
A NEW WHALEBONE WHALE 11
External to the anterior process of the periotic, the ventral
surface of the squamosal is hollowed out, forming a shal-
low concavity, widest anteriorly, which extends forward
obliquely from the posterointernal angle of the postglenoid
process to near the glenoid angle of the squamosal, and also
downward on the inner face of the postglenoid process.
On the ventral surface of the skull, the squamosal forms
the outer and the major portion of the hinder boundary of
the temporal fossa, the internal margin being coextensive
with the outer edge of the pterygoid. External to the
pterygoid fossa and behind the posteroexternal angle of the
pterygoid is the large foramen ovale, which transmits the
mandibular branch of the trigeminal nerve. This foramen
is located in the bifurcation between the falciform and glen-
oid processes of the squamosal, which are suturally united
in front with the pterygoid. ~The maximum anteroposterior
diameter of the foramen ovale is 20 mm., and its maximum
verticle diameter is 10 mm. The falciform process of the
squamosal is convex in both directions, and its internal
border overhangs a portion of the tympanoperiotic recess,
as well as the hinder end of the oterygoid fossa.
The thickened exoccipitals constitute the most backwardly
projecting elements of the skull. The paroccipital processes
are merely roughened areas on the ventral edge of the
exoccipital. The occipital condyles are separated medially
by a deep very narrow groove.
The left jugal, which when in normal position provides
the inverted arch below the orbital rim of the supraorbital
process of the frontal, was detached from the skull when
found. The posterior end (pl. 3, fig. 2) of this bone (di-
ameter, 50-++mm.) is attenuated and bent almost at right
angles to the adjacent more flattened horizontal portion.
The external and internal edges of the horizontal portion
are founded and about equal in thickness. The proximal
end (pl. 3, fig. 1), which is obliquely truncated, is much
thinner and more markedly flattened; it is compressed for a
distance of 55 mm. and is turned upward. This flat end
may have been inserted between the preorbital angle of the
supraorbital process of the frontal and the posterior ventral
overriding plate of the maxillary. The greatest width of
the jugal is 50 mm. The length of this left jugal in a
straight line is 152 mm.
Measurements (in mm.) of the skull of USNM 11976
are as follows:
Greatest length of skull, anterior end of left premaxil-
1965
lary to level of posteroexternal angle of exoccipital
Distance between anterior end of right premaxillary 1895
and posterior articular face of right occipital condyle
Distance between anterior end of right premaxillary 1550
and apex of supraoccipital shield
Length of rostrum, level of antorbital notches to end 1350
of left premaxillary
Greatest length of right premaxillary 1455
Distance between anterior end of right premaxillary 1345
and anterior end of right nasal bone
Distance from apex of supraoccipital shield to pos- go
terior end of right nasal bone
Greatest length of right nasal bone II5
Combined width of nasal bones, anteriorly 30
Combined width of nasal bones at hinder ends 10
Transverse distance between outside margins of pre- 73
maxillaries at level of anterior ends of nasal bones
Maximum transverse distance between outside margins 225
of premaxillaries at level of anterior ends of maxil-
laries
Transverse diameter of skull across posteroexternal 865
angles of supraorbital processes
Greatest anteroposterior diameter of extremity of left 186
supraorbital process
Transverse diameter of skull across outer surfaces of 945
zygomatic processes
Transverse diameter of skull between outer margins of 610
exoccipitals
Transverse distance between outer margins of occipital 183
condyles
Greatest or obliquovertical diameter of right occipital 95
condyle
Greatest transverse diameter of right occipital condyle 79
Greatest transverse diameter of foramen magnum 48
Distance from dorsal rim of foramen magnum to apex 325
of supraoccipital shield
Greatest length of left zygomatic process, extremity of 380
postglenoid process to anterior end of zygoma
Greatest breadth of basioccipital across lateral pro- 226
tuberances, outside measurement
Least intertemporal diameter of cranium on ventral 215
face
Greatest anteroposterior diameter of left palatine bone 310
Maximum transverse diameter of left palatine bone 100+
Distance from posterior end of vomer to anteriorend of 405
palatine bone
Distance between opposite foramina ovale 302
Tympanic Bulla
Although both tympanic bullae (USNM 11976) were
associated with the periotics when the skull was excavated,
the left bulla is crushed and broken; the right bulla is
complete except for the terminal portion of the posterior
process and the anterior pedicle. The right tympanic
bulla was detached for study and description. This
tympanic bulla possessed the normal thin attachments to
the periotic, one anterior and the other posterior. In
shape, the bulla resembles somewhat that of Partetobalaena
palmeri, but is larger, the anterior end being proportionately
wider and the ventral face less convex. The right tympanic
bulla is sufficiently well preserved to show the contour of
the epitympanic recess or tympanic cavity (pl. 3, fig. 4),
which is bounded externally by the brittle, thin overarching
12 UNITED STATES NATIONAL MUSEUM BULLETIN 247
outer lip, internally by the involucrum, as well as the size
and shape of the anterior outlet or tympanic aperture of
the eustachian canal.
The posterior process (pl. 3, fig. 4) projected in front
from the hinder end of the involucrum and behind from the
posterior edge of the thin outer lip. In cross section, the
posterior pedicle at the base resembles a compressed ‘‘V”
in contrast to the open ‘“‘U” of Parietobalaena palmeri.
The anterior pedicle of the bulla, which is ankylosed to
the periotic, is broken off at the level of the free edge of the
outer lip. The bluntly rounded extremity of the sigmoid
process (pl. 3, fig. 3) is twisted at right angles to the
longitudinal axis of the bulla, its anterior face is convex and
its posterior face deeply excavated. There is a deep,
broad vertical furrow on the outer lip (fig. 4a) in front of
the sigmoid process. A deep narrow groove separates this
sigmoid process from the so-called conical apophysis of
Beauregard which is blunt, rounded and projects slightly
below the level of the involucrum.
FicureE 4.—Views of right tympanic bulla) USNM 11976, of
Pelocetus calvertensis: a, external view; b, dorsal view. Abbrs.:
inv., involucrum; pr.m., processus medius or conical apophysis;
pr.p., base of pedicle of posterior process; pr.s., sigmoid
process.
PART 1
The involucrum (fig. 4b) attains its maximum width
posteriorly, particularly on the posterior third of its length,
and then becomes strongly narrowed toward the anterior
outlet. Internally, the dorsal face of the involucrum is
roughened by closely spaced transverse creases.
In ventral aspect the tympanic bulla is characterized by
an obliquely truncated anterior end which is wider than
the more rounded posterior end, although the profile of
both ends slopes obliquely backward from internal to
external angles. Viewed from the side, the ventral profile
is not depressed medially.
Measurements (in mm.) of right tympanic bulla of
USNM 11976 are as follows:
Greatest length of tympanic bulla 64
Greatest width of tympanic bulla 35
Greatest depth of tympanic bulla on internal side 39
Greatest depth of tympanic bulla on external side, ventral 52. 5
face to tip of sigmoid process
Thickness of lip of bulla at anterior outlet 4
Periotic
On the type skull (USNM 11976) the posterior process
(fig. 5) is unusually elongated, expanded distally to more
than twice (65 mm.) its proximal width (24 mm.), and
relatively narrow for more than two-thirds of its length.
This process is firmly wedged in a deep groove between the
exoccipital and the postglenoid portion of the squamosal.
The pars cochlearis projects into a large recess behind the
pterygoid fossa and its short stout anterior process is lodged
in a cavity or rather deep excavation in the squamosal.
The posterior pedicle of the tympanic bulla, before it broke
off, was fused with the internal end of the rather broad ridge
that parallels the anterior edge of the ventral face of the
posterior process. Behind this ridge is a deep broad groove,
which in Recent mysticetes is traversed by the facial nerve
on its outward course. The external denser portion of the
periotic is lodged in the deep cavity occupied in part by the
anterior process and is hidden for the most part by the over-
hanging internal edge of the squamosal; it is, however,
compressed from side to side. The anterior process is
rather short, very broad, and its extremity is emarginate
and pitted.
The pars cochlearis is markedly compressed transversely,
its anteroposterior diameter (33 mm.) is at least twice its
width (16 mm.). Externally, the pars cochlearis rises almost
vertically to the inner margin of the fenestra ovalis; and its
ventral or tympanic surface is convex in both directions.
Viewed from the ventral side, the cerebral profile of the
pars cochlearis is sinuous and the posterior face is abruptly
truncated above the very large fenestra rotunda.
A very narrow rim encircles the fenestra ovalis, which is
elevated above the level of the channel for the facial nerve.
A NEW WHALEBONE WHALE 13
Ficure 5.—Ventral view of right periotic, USNM 11976, of Pelocetus calvertensts.
Abbrs.: Bo., basioccipital; Ex.oc., exoccipital; f.ov.,
foramen ovale; j.n., jugular notch or incisure; |.pr., lateral or descending process of basioccipital; m.e.a., channel for external audi-
tory meatus; p.c., pars cochlearis; Per., periotic; pgl., postglenoid process; pr.a., anterior process of periotic; pr.p., posterior process
of periotic; Pt., pterygoid; pt.f., pterygoid fossa; Sq., squamosal; zyg., zygomatic process.
This fenestra ovalis is largely concealed from a tympanic view
by the overhanging external face of the pars cochlearis. A
thin carina intervenes between this channel for the facial
nerve and the fenestra ovalis. Small orifices of the semicir-
cular canals are visible at the bottom and on the outer wall
of the vestibule. There is a deep and narrow groove extend-
ing forward from the external rim of the fenestra ovalis through
the notch between the pars cochlearis and the anterior process.
The fossa for the stapedial muscle is rugose, broader than
long and extends downward on the internal face of the
posterior process and on the external face of the pars
cochlearis.
A large shallow concavity (pl. 16, fig. 2) for reception of
the head of the malleus is situated adjacent and external to
the epitympanic orifice of the aquaeductus Fallopii. The
precise margins of this articular facet are not clearly indi-
cated, but it appears to be continuous externally with the
depressed area on the outer denser portion of the periotic.
In front of this facet the base of the slender anterior pedicle
of the tympanic bulla is fused with the anterior process.
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A NEW WHALEBONE WHALE 15
The fossa incudis may be described as a small pit located on
the outer denser portion of the periotic external to the
channel for the facial nerve and posterior to the area of
attachment of the anterior pedicle of the tympanic bulla.
The structural peculiarities of the cerebral face of the
pars cochlearis are often diagnostic. Below the apex of
the pars cochlearis is the internal acoustic meatus at the
bottom of which is the spiral tract and a minute foramen
singulare, which on this type specimen can only be seen with
the aid of a mirror. The description of the cerebral face
will be based largely on the left periotic (USNM 23059)
of the referred specimen. Because of the oblique incli-
nation of the encircling wall of this meatus, the ¢ractus
spiralis foraminosus is partially concealed from a cerebral
view (pl. 16, fig. 3). A thick osseous partition (7.5 mm.)
separates the large entrance to the aqueduct of Fallopius
from the more centrally located internal acoustic meatus.
This cerebral entrance to the Fallopian aqueduct opens
into a deep excavation on the anterointernal face of the
pars cochlearis. Posterior to this meatus is the small orifice
of the aqueduct of the cochlea and above the latter is the
large deep fossa into which the aqueduct of the vestibule
opens. The area of this somewhat triangular vestibular
fossa is almost as large as the area encircled by the cere-
bral rim of the internal acoustic meatus. Between this
vestibular fossa and the vertically elongated rim of the
internal acoustic meatus is a rather blunt projection. The
smooth convex surface of the tympanic face of the pars
cochlearis does not extend inward as far as the rim of the
internal acoustic meatus, and the irregular margin re-
sulting threfrom accentuates the rugose appearance of the
cerebral face. On the cerebral side also, the dorsal borders
of the pars cochlearis and the anterior process are pitted and
spongy, transversely compressed and extended inward and
forward.
Measurements (in mm.) of periotics are as follows:
Right Left
USNM USNM
11976 23059
Length of posterior process, distance 210 135
from external end to outer wall of
groove for facial nerve
Greatest dorsoventral depth of periotic 40 45
(from most inflated portion of tym-
panic face of pars cochlearis and ex-
ternal excavation to most projecting
point on cerebral face)
Distance between epitympanic orifice 56 45
of aquaeductus Fallopiu and extremity of
anterior process
Distance from external end of posterior
process to anterior end of anterior
process (in a straight line)
Mandibles
Both of the mandibles (USNM 11976) associated with
the skull are incompletely preserved and lack a considerable
portion of their dorsal borders above the level of the series
of external nutrient foramina. In general proportions these
mandibles are considerably more robust and exhibit a
relatively much deeper horizontal ramus than any of the
other Calvert cetotheres heretofore discovered. The
anterior ends of both of these mandibles are missing. The
internal surface of each mandible is distinctly flattened,
especially on the anterior three-fourths. The dorsoventral
convex curvature of the external face of the mandible is
quite pronounced and the maximum transverse diameter
is below the center of the height of the horizontal ramus.
The right mandible measures 73 mm. transversely at a
point 1135 mm. (in a straight line) anterior to the posterior
articular face of the condyle. The ventral face of the middle
portion of the horizontal ramus is almost flat. Anteriorly
for a distance of 220 mm. from the apex of the coronoid
process a sufficient portion of the dorsal border of the
horizontal ramus of the right mandible is preserved to show
that it is abruptly compressed to form a narrow longitudinal
ridge.
Both of these mandibles are bowed outward (fig. 6b) and
their original length (1900+-mm.) was undoubtedly
greater than the distance from the glenoid face of the post-
glenoid process to the extremity of the corresponding pre-
maxillary (1820 mm.). Viewed from the side the ventral
profile of the mandible exhibits a slight convex curvature.
One mental foramen is preserved on the right mandible
some 1480 mm. anterior to the articular face of the condyle
and it opens into a groove that leads horizontally forward.
On the left mandible (fig. 6a) one and vestiges of two others
in the external series of nutrient mental foramina are pre-
served. On this left mandible, the most posterior of these
external mental foramina is located 665 mm. anterior to
the posterior articular face of the condyle. These foramina
are relatively large and apparently drop to a lower level
toward the anterior end of the mandible. Each of these
mental foramina opens into a groove, which not only is
directed forward, but also increases in width from its
orifice to the point where it becomes indistinct. On both
mandibles the small internal foramina forming the longi-
tudinal alveolar series, which normally runs forward below
the upper edge of the mandible, were destroyed.
The large coronoid process is low, subtriangular, termi-
nating in an everted apex, the anterior and posterior edges
displaying a convex curvature, the inner face convex and
the outer face strongly concave. The apex of the coronoid
process bends strongly outward, above and anterior to the
internal orifice for the large mandibular canal. Behind
16 UNITED STATES NATIONAL MUSEUM BULLETIN 247
the apex the posterior edge of the coronoid process becomes
thickened (31 mm.) in contrast to the thin anterior edge.
The condyle (fig. 6c) is quite large, expanded from side
to side and convex in all directions. Dorsally the condyle
is strongly compressed, especially from the inner side,
narrowing the articular face to some 34 mm. on the left
mandible. The maximum transverse diameter (130 mm.)
of the condyle of the left mandible is slightly below the
center. Ventrally the condyle maintains its width; it is
bounded by a wide furrow between its internal border and
the angle of the condyle. The angle of the mandible is
robust and well developed. The outer border of the
condyle projects noticeably outward and less so forward.
The distance from the articular face of the condyle to center
of the apex of the coronoid process is 270 mm. The
distance from the articular face of the condyle to the
orifice of the mandibular (dental) canal is 235 mm. on the
light mandible.
Well preserved anterior ends of two right mandibles
obtained elsewhere from the Calvert Cliffs are referred to
this species. The largest one (USNM 21306) measures 405
mm. in length; its vertical diameter 100 mm. behind the
anterior end is 166 mm., and at a point 200 mm. behind,
172 mm. This fragment compares most favorably with
the measurements of the two above described mandibles.
The other slightly smaller mandible (USNM 14693,
fig. 7) measures 445 mm. in length; its vertical diameter at
both 100 and 200 mm. behind the anterior end is 147 mm.
The dorsal faces of both of these mandibular ends are
noticeably broader than the ventral faces. On both of
these mandibles the symphysis is quite short, the roughened
area not exceeding 70 to 80 mm. The groove on the
dorsal face (USNM 21306) terminates in an anteriorly
directed foramen. This groove represents the anterior
continuation of the series of small internal foramina which
move up to the dorsal face of the ramus to join this groove
of fissure at its posterior end. Above the ventral edge of
this anterior section and below the longitudinal crease, the
lower border of the internal face is depressed along a
strip measuring 55 mm. dorsoventrally.
PART 1
Measurements (in mm.) of mandibles of USNM 11976
are as follows:
Right Left
Greatest length of mandible along out- 1690 1610
side curvature, as preserved
Greatest length of mandible in a straight 1650 1540
line, as preserved
Greatest vertical diameter of mandible = 150
at a point 670 mm. anterior to pos-
terior articular face of condyle
Greatest vertical diameter at coronoid 214.5 212
process
Greatest transverse diameter of ramus 85.5 78
at coronoid process
Least vertical diameter of mandible 125 127.5
behind coronoid process
Greatest vertical diameter of condyle 185 —
Greatest transverse diameter of condyle 126 130
Greatest vertical diameter of hinder end 196
of mandible, including condyle
Center of apex of coronoid process to 270 280
posterior articular face of condyle
Hyoid Bones
Unlike those of balaenopterine whales the great horns
(thyrohyals) of this hyoid (fig. 8a) are directed backward
as well as upturned, and are progressively attenuated beyond
the middle of their length toward their rugose ends which
are pitted for the attachment of cartilage. No line of
demarcation can be discerned between the relatively small
basihyal and the large slightly flattened hornlike thyrohyals.
The area on the front edge of the central portion (basihyal),
where the pair of anterior conical processes (certaophyals)
are normally located on the mysticete basihyal, is eroded to
such an extent that the original appearance can only be
surmised. Cartilages connecting with an end of the corre-
sponding stylohyal are attached to each of the conical
processes. The basihyal is more noticeably compressed
dorsoventrally than either thyrohyal and exhibits a shal-
ES
=)
Ficure 7.—Internal view of anterior end of right mandible, USNM 14693, of Pelocetus calvertensis.
A NEW WHALEBONE WHALE 17
Ficure 8.—Views of hyoid bones, USNM 11976, of Pelocetus calvertensis: a, dorsal view of
basihyal and ankylosed thyrohyals; 5, ventral view of right stylohyal.
basihyal; t.hy., thyrohyals.
lowly concave posterior margin and a protuberant convex
anterior margin. The thyrohyals are robust, dilated antero-
posteriorly near the middle of their length which results in
an angular deflection of the posterior profile in contrast to
the slightly concave anterior profile. The stylohyal re-
sembles in some respects those of Balaenoptera acuto-rostrata.
The right stylohyal (fig. 8b) is essentially complete except
for the eroded proximal extremity. This bone is noticeably
flattened except at the enlarged and pitted end which is
connected by cartilage with the corresponding anterior
conical process of the basihyal. This stylohyal is also
markedly widened anteroposteriorly, producing a pro-
nounced bulge on the posterior profile.
Measurements (in mm.) of the hyoid bones of USNM
11976 are as follows:
Maximum transverse diameter of hyoid between ex- 333
tremities of great horns (thyrohyals)
Anteroposterior diameter of central portion (basihyal) 62
Maximum thickness of central portion (basihyal) 22
Maximum anteroposterior diameter of great horn 51
(thyrohyal)
Maximum thickness of great horn (thyrohyal) 33
Maximum diameter of great horn (thyrohyal) at outer 25
end
Length of right stylohyal 224+
Maximum diameter of the end of stylohyal connected ‘50
to ceratohyal
Maximum anteroposterior diameter of stylohyal 65
Maximum thickness of stylohyal at same point 22.5
Abbrs.: b.hy.,
Vertebrae
Since the epiphyses are firmly ankylosed to the centrum
of all the cervical, dorsal, lumbar and caudal vertebrae of
both the type specimen (USNM 11976) and the referred
specimen (USNM 23059) both whales were physically fully
mature.
CERVICAL VERTEBRAE.—AlI] of the cervical vertebrae
(USNM 11976), except the fifth, were found behind the
skull when it was excavated. These vertebrae were partially
visible on the surface of the compact bluish sandy clay
whose exposed bayward sloping surface was being scoured
by the sand in the tidal wash. Souvenir seekers also had
unsuccessfully attempted to extricate some of the vertebrae.
As a result the neural arches and the lateral processes of
the cervicals in the series behind the third as well as those of
several dorsals were either damaged or destroyed.
All of the cervical vertebrae with the exception of the axis
and the third cervical were free. The diagnostic features
of this series are summarized as follows: Atlas massive, with
stout neural spine, robust transverse processes, and short
hyapophysial process; axis characterized by absence of a
neural spine, a short and blunt odontoid process, and large
dorsoventrally widened as well as elongated transverse
processes; upper and lower transverse processes of third
cervical elongated and united externally to inclose the large
vascular mass; fourth to seventh cervicals characterized by
a broad flattened centrum, narrow pedicle (neurapophysis),
and rather wide neural canal.
18 UNITED STATES NATIONAL MUSEUM BULLETIN 247
Atlas: Except for a portion of the neural spine the atlas
(USNM 11976) is well preserved. It is relatively large as
compared to those of other Calvert cetotheres. This massive
atlas (fig. 9a) measures 176 mm. between the outer margins
of the anterior facets for articulation with the occipital
condyles of the skull, each facet being deeply concave,
broadest ventrally, and inclined obliquely outward; these
two facets are separated ventrally by a rather narrow
interval (7 mm.). The neural arch (pl. 4, fig. 6) is rather
broad anteroposteriorly. On each side the arch (neura-
pophysis) is pierced ventrally near the middle of its length
(fig. 9c) by a large vertebra-arterial canal, which opens into
a broad ventrally directed groove. The neural spine, judg-
ing from the broken basal edges, was rather robust. ‘The
transverse process on each side of the atlas is massive and
Wyy
D
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NAS
PART 1
directed more outward than backward, attenuated distally»
and terminating in a blunt extremity. The neural canal
(pl. 4, fig. 1) is large, but partially obstructed ventrally by
a pair of osseous excrescences.
The two opposite posterior facets (fig. 9b) for articulation
with the axis are very broad, but their external margins are
not sharply set off from the posterior face of the centrum.
The hyapophysial process below the neural canal is low,
bluntly pointed and irregularly pitted or roughened.
Between the opposite posterior facets and below the neural
canal is a broad upwardly sloping surface for articulation
with the odontoid process of the axis.
All of the Calvert Miocene cetothere atlases available for
study have a reduced and unobtrusive hyapophysial process
on the posteroventral border of the centrum and but one
Bayon
ai W\\Y' my
FicurE 9.—Views of atlas, USNM 11976, of Pelocetus calvertensis: a, anterior view; 6, posterior view;
c, lateral view. Abbrs.: hyp., hyapophysial process; tr., transverse process.
A NEW WHALEBONE WHALE 19
0d.
FicurE 10.—Anterior view of axis, USNM 11976, of Pelocetus calvertensis.
Abbrs.: od., odontoid process; tr., transverse process.
transverse process on each lateral face. Conversely, the
atlases of all the Calvert Miocene odontocetes possess a
prominent and often noticeably elongated or enlarged
hyapophysial process and usually a fairly well developed
lower (parapophysis) and a variably developed upper
(diapophysis) transverse process.
On the atlas (USNM 23059, pl. 3, fig. 5) of the referred
specimen, the distance (183 mm.) between the outer mar-
gins of the anterior facets for articulation with the occipital
condyles of the skull exceeds slightly the same measurement
of the type atlas, yet the anteroposterior diameter (72 mm.)
of the centrum is less. Both transverse processes of this
referred atlas are eroded. The two posterior facets for
articulation with the axis are slightly larger than those of the
type atlas, but no hyapophysial process below the neural
canal is developed as a distinct entity. The usual broad
upward sloping surface for articulation with the odontoid
process of the axis is present between the opposite large
articular facets.
Additional measurements of this referred atlas are as
follows: Vertical diameter of axis, tip of neural spine to
ventral face of centrum, 163+ mm.; maximum vertical
diameter of neural canal anteriorly, 80 mm.; maximum
transverse diameter of neural canal, 57 mm.; maximum
distance between outer ends of diapophyses, 142+ mm.;
and least anteroposterior diameter of right pedicle of neural
arch, 54 mm.
Axis: The axis (pl. 4, fig. 2) is solidly fused with the third
cervical (pl. 4, fig. 7), not only between the centra but also
between the post- and pre-metapophysial facets. ‘The
transverse diameter (388 mm.) of the axis (fig. 10) is greater
than twice its vertical diameter (165 mm.). Each ventral
transverse process is massive, elongated, dorsoventrally
widened, and diminishes slightly in height to the bluntly
truncated outer end. The height (56.5 mm.) of the neural
canal anteriorly is less than the transverse diameter (63 mm.)
The anterior facets for articulation with the atlas are shal-
lowly concave from side to side, the vertical diameter (103
mim.) of the right facet being considerably greater than the
minimum transverse diameter (60 mm.) and they are
separated ventrally by an interval of approximately 25 mm.
The odontoid process is large, wider than high, rugose dor-
sally, and not noticeably elongated (fig. 10). The anky-
losis of the centra of the axis and the third cervical is so
complete (fig. 11) that all evidence of coalescence is oblit-
erated on the lateral and ventral surfaces of these two
centra, but not dorsally on the floor of the neural canal
where a distinct separation exists, the anteroposterior di-
ameter of the centrum of the third cervical being 34 mm.
Figure 11.—Lateral view of ankylosed axis and third cervical,
USNM 11976, of Pelocetus calvertensis. Abbrs.: od., odontoid
process; tr., transverse process.
20 UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 1
Ficure 12.—Posterior view of third cervical and axis, USNM 11976, of Pelocetus calvertensis.
Abbr.: tr., transverse process.
Neither transverse process is perforated by the foramen
transversaria, and no trace of this aperture is visible on the
anterior face of this process; on the posterior face (fig. 12),
however, close to the base on each process is a circular
depression approximately 35 x 20 mm. in diameter which
indicates the former course of the cervical extension of the
thoracic retia mirabile. It seems possible that this foramen
may have been closed during growth by the exostosis which
has affected several vertebrae in the column.
The neural arch is stout, measuring 70 mm. antero-
posteriorly at the apex of the coalesced arch, but actually
43 mm. on each pedicle at the level of the floor of the neural
canal. A sharp edged anteroposterior crest on the dorsal
surface of the neural arch persists as a vestige of the neural
spine. The dorsal surface of the centrum is depressed and
the ventral surface is excavated shallowly on each side of
the broad median longitudinal ridge.
Third Cervical: In contrast to the axis, the third cervical
(fig. 12) is less massively constructed even though the
centrum is rather broad (140 mm.), but its anteroposterior
diameter (34 mm.) is less. The concave posterior surface
of the centrum has raised margins. A median antero-
posterior ridge on the dorsal and ventral face of the centrum
separate shallow depressions. The relatively slender pedi-
cles (pl. 4, fig. 7) of the neural arch (anteroposterior di-
ameter, 18-20 mm.) support rather short anterior zyga-
pophyses which are fused with corresponding lateral sur-
faces on the neural arch of the axis. The postzygaphyses
are elongated, rodlike and project at least 10 mm. beyond
the level of the hinder face of the centrum. The neural
canal is slightly wider (68 mm. posteriorly) than that of
the axis. The upper (diapophysis) and lower (para-
pophysis) transverse processes are elongated and slender and
unite or are ankylosed externally, inclosing a very large
lateral foramen (foramen transversaria). This large com-
pletely bounded opening or foramen incloses a large
vascular mass, the cervical extension of the thoracic
retia mirabile in recent balaenopterine whales (Walmsley,
1938). The vertical diameter of this foramen on the right
side is 50 mm. The extremity of the lower transverse
process is prolonged about 48 mm. outward beyond the
outer wall or limit of this foramen; it is expanded distally
in a dorsoventral direction and bent backward dorsally
(fig. 12). The lower transverse process is stouter and much
broader near the centrum than the upper, and its upper and
lower surfaces are rounded. Both the upper and lower
transverse processes are incomplete externally on the
left side.
Fourth Cervical: The fourth, sixth and seventh cervical
vertebrae have a broad anteriorly and posteriorly flattened
centrum, narrow pedicle for the neural arch and a rather
wide neural canal. On the fourth cervical (pl. 4, fig. 3)
a 90 mm. basal portion of the right lower transverse
process is attached to the centrum, but the left process
is broken off at the base. The lower transverse process is
rather slender, directed more outward than downward,
and projects outward with a twist, the outer portion
being anteroposteriorly compressed. The short inner
section of the upper transverse process indicates that it
also was slender. The dorsoventral gap (at least 60 mm.)
suggests that the large lateral foramen may have been
larger than that of the third cervical. The pedicle of the
neural arch (pl. 4, fig. 8) preserved on the right side is
relatively short and low, its minimum anteroposterior
diameter being 22 mm. The prezygapophysial facet is
shallowly concave and longer (20 mm.) than wide (18 mm.).
The ventral articular facet on the right postzygapophysis
projects backward 20 mm. beyond the hinder face of the
A NEW WHALEBONE WHALE 21
centrum. On the dorsal and ventral faces of the centrum
the anteroposterior ridges are low and broad, separating
opposite depressed areas. The rims of the anterior and
posterior faces of the centrum project beyond and over-
hang the lateral faces.
Sixth Cervical: On both sides of the centrum (pl. 4,
fig. 4), the upper and lower transverse processes are broken
off 10 to 20 mm. beyond their point of origin. The sixth
cervical is characterized in part by a change in the direction
of its transverse processes, the upper process instead of
being directed outward in a line with the transverse axis
of the centrum was projected somewhat forward as well
as outward at least at the base; the ventral process was rather
slender at the base and directed more downward than
outward. The pedicle (pl. 4, fig. 9) supporting this ventral
transverse process was obviously stronger than the pedicle
for the upper transverse process. A thin lamina, compressed
amteroposteriorly, which has its origin on the anterolateral
border of the centrum but joined dorsally to the base of
the pedicle of the neural arch supports the upper transverse
processes. Both pedicles (neurapophyses) are wider trans-
versely (34 mm.) than anteroposteriorly (19 mm.) near
the base.
The anterior face of the centrum is depressed, shallowly
concave, its elevated rims projecting beyond and overhang-
ing the lateral faces. The anteroposterior ridge separating
the lateral depressions is broader and more conspicuously
developed on the ventral face than on the dorsal face.
Seventh Cervical: The anterior face of the centrum
(pl. 4, fig. 5) is shallowly concave and its rim is not elevated
but does project beyond the ventral face; the posterior
face is nearly flat. The median anteroposterior ridge on
the ventral face is decidedly more prominent than the
corresponding ridge on the dorsal face. No ventral
transverse process is present, a characteristic of the
mysticetes. The broad dorsoventrally widened lamina
supporting the upper tramsverse process is noticeably
larger than the corresponding structure on the sixth
cervical in conformity with the dimensions of this process,
its posterior surface passing imperceptibly into that of the
neural arch. A broken surface area on the anteroventral
portion of this broad lamina suggests that the diapophysis
may have had its origin either here or on the similar area
located on the upper external border of this lamina.
Presumably this process was directed somewhat forward and
downward and then outward. The prezygapophysial
articular facet is preserved on the left side, its inner margin
being less than 15 mm. above the floor of the neural canal.
The minimum diameter of the left pedicle of the neural
arch is 40 mm. transversely and 20 mm. anteroposteriorly,
Measurements (in mm.) of cervical vertebrae of USNM
11976 are as follows:
Atlas
Maximum vertical diameter of vertebra, tip of 158+
neural spine to ventral face of centrum
Maximum anteroposterior diameter of centrum 96 #
Maximum vertical diameter of centrum anteriorly =
Maximum transverse diameter of centrum an- =
teriorly
Maximum vertical diameter of neural canal, 70
anteriorly
Maximum transverse diameter of neural canal, 55
anteriorly
Maximum distance between outer surfaces of 266
diapophyses
Maximum distance between outer surfaces of =
parapophyses
Least anteroposterior diameter of right pedicle of 52.3
neural arch
Maximum distance between outer margins of 176
anterior articular facets
Axis C3 C.4 C5 C.6 C7
165 — = a aan ung
79° 35 36 mt 37-7 38
93 © 100 © 99 aa 96. 5 95
= 140 ° 129 = 138 114
56. 5 — = = a —
63 67.5 — — 84 za
— 296 — = — ==
388 306+ 284-5 = = —
63 18.2 20 a as ul
162 — = _ aes plik
a Dorsally.
b Plus odontoid process.
© Posteriorly.
22 UNITED STATES NATIONAL MUSEUM BULLETIN 247
DorSAL VERTEBRAE.—All of the epiphyses on the nine
dorsal vertebrae (USNM 11976) excavated at the site are
firmly ankylosed to the centra and this condition in Recent
mysticetes is regarded as evidence of physical maturity. In-
asmuch as each dorsal vertebra has attached to the distal end
of its transverse processes a pair of ribs which in succession
contribute their share of the framework for the thorax, this
series of vertebrae must correspond at a minimum to the
number of here associated ribs. When these externally dif-
ferent ribs are arranged in what appears to be their normal
sequential positions and placed in contact with correspond-
ing articular surfaces, the conclusion is inescapable that
twelve vertebrae comprised the dorsal series. The centra in-
crease in length from the first to the twelfth dorsal and all are
broader than high. The breadth also exceeds the length of
the centrum of all the dorsal vertebrae. The outline of the
anterior end of the centrum of the first to the tenth dorsals is
subcordate. On each side of the centrum of the first to
eighth dorsals inclusive, below the level of the floor of the
neural canal and adjacent to the edge of the posterior face of
the centrum, there is an articular facet for the accomodation
of the following rib. Furthermore, the facet for the capitu-
lum of the following ribs is gradually but progressively lo-
cated higher on the lateral surface of the centrum from the
first to the eighth dorsal. Although the centra of the dorsal
vertebrae of Recent balaenopterine whales lack these facets,
capitular articular surfaces are located posteroexternally on
the centra of adult Eubalaena glacialis (Turner, 1913, p. 905)
and Balaena mysticetus (Eschricht and Reinhardt, 1866, p.
116).
The neural canal decreases in width and increases in
height from the first to twelfth dorsals. The pedicles
(neurapophyses) of the neural arch of the eight anterior
dorsals are massive and unusually thick; they occupy more
than half the length of the centrum on all the dorsals.
The diapophyses become progressively more robust. The
transverse processes (diapophyses) of the first five dorsals
arise partly from the neural arch and partly from the ex-
ternal face of the centrum, while on the ninth, tenth,
eleventh and twelfth dorsals (USNM 23058) the transverse
processes are derived from the centrum. On the six
anterior dorsals the outer or terminal facet for articulation
with the tuberculum of the corresponding rib is located for
the most part anterior to the level of the anterior face of
the centrum. ‘This facet for the tuberculum is located
almost vertically on the attenuated extremity of the antero-
posteriorly compressed diapophysis of the second dorsal,
obliquely on that of the third dorsal and is conspicuously
and progressively elongated horizontally on the fourth to
twelfth dorsals inclusive. The neural spines increase in
heighth from the first to the twelfth dorsals.
The width of the interval separating the prezygapophysial
facets seems to decrease markedly from the anterior to the
PART 1
posterior end of the dorsal series and behind the sixth dorsal,
the width of the interval separating the prezygapophysial
facets become markedly reduced. The prezygapophysial
facets of the first to sixth dorsal vertebrae are large, elon-
gated, deeply concave and slope steeply from outer to
inner margin. On the sixth, seventh, and eighth dorsals
at least the backwardly projecting dorsal portion of the
neural arch and the postzygapophysial facets extend back-
ward beyond the level of the posterior face of the centrum
and are firmly clasped by the prezygapophysial facets and
metapophyses of the next dorsal.
Since some of the vertebrae are missing in the dorsal
series of USNM 11976, it is fortunate that four consecutive
posterior dorsals of a mature individual were associated
with the skeletal remains of USNM 23058. In the text
that follows the vertebrae will be described under one or
both of these numbers as indicated.
First Dorsal: The centrum (USNM 11976, pl. 6, fig. 6)
is more massive and thicker than that of the seventh
cervical. The vertical diameter of the centrum anteriorly
is 88 mm. Although the transverse process (diapophysis)
is broken off on both sides (pl. 5, fig. 1) near its origin, the
remnant preserved shows that each process arises partly from
the neural arch and partly from the dorsoexternal angle of
the centrum. Furthermore, the basal portion of the
neural arch (neurapophysis) preserved on the right side
indicates that the forward curvature of the upper transverse
process was apparently more accentuated than that of the
seventh cervical. At the base of the anteroposterior
diameter of the pedicle (neurapophysis) of the neural arch
does not exceed 25 mm., and the transverse diameter of the
neural canal on its floor was 80 mm. _A fairly large articular
facet with elevated margins is located on the lower postero-
external angle of the centrum for the accommodation of
the capitulum of the following or second rib.
Second Dorsal: The rather slender transverse process
(diapophysis) of this dorsal (USNM 11976, pl. 5, fig. 4)
is continuous at its thickened base with the pedicle of the
neural arch and the dorsoexternal angle of the centrum,
and is projected forward and outward. In cross section the
left diapophysis (pl. 6, fig. 2) is compressed anteroposteriorly
and the articular facet on its extremity for reception of the
tuberculum of the second rib is narrow and nearly vertical
in position. The distance between the ends of the opposite
diapophyses is estimated to be 290+ mm. The centrum
is larger, both in breadth (118 mm.) and thickness (47.5
mm.) than the first dorsal. The left pedicle of the neural
arch is low, widened transversely and measures 26 mm.
anteroposteriorly. The transverse diameter of the neural
canal is 82 mm. On the left side the elongated, concave
prezygapophysial facet measures 60 mm. in length and
23 mm. in width. The facet (pl. 6, fig. 7) for the capitulum
of the third rib is smaller than that on the preceding dorsal.
A NEW WHALEBONE WHALE 23
FIGURE 13.—Anterior view of third dorsal, USNM 11976, of
Pelocetus calvertensis.
Third Dorsal: This dorsal (pl. 5, fig. 2) is notably larger
and more massive than the second dorsal. A marked
increase occurs in the dimensions of the diapophysis
which projects outward and is inclined obliquely forward,
its dorsal profile sloping to the extremity. The thickened
basal portion of the right diapophysis (fig. 13) likewise
arises from the transversely broadened pedicle (right,
width 54 mm.) of the neural arch and the dorsoexternal
angle of the centrum. The concave articular facet (length,
50 mm.) on the extremity of the diapophysis for reception
of the tuberculum of the rib is elongated and is directed
obliquely from above and in front downward and back-
ward. The distance between the ends of the opposite
diapophyses is 292 mm. ‘The left pedicle of the neural arch
measures 35 mm. anteroposteriorly at its base. The
elongated prezygapophysial facet (pl. 6, fig. 3) is deeply
concave in an anteroposterior direction, shallowly concave
from side to side, and slopes obliquely inward and down-
ward from its outer margin, The left metapophysis is a
bluntly pointed anterior projection. The neural canal
near its floor measures 75 mm. transversely. The antero-
posterior increase in the thickness of the centrum (58 mm.)
is proportionately greater than the increase in its transvese
diameter anteriorly. The flattened facet (pl. 6, fig. 8) for
the capitulum of the fourth rib is flush with the posterior
face of the lateral surface of the centrum.
Fourth Dorsal: A less noticeable increase in the thickness
(67 mm.) of the centrum (pl. 6, fig. 4) of the fourth dorsal
(USNM 11976) is observable and but very little if any
change in the dorsoventral diameter (82 mm.) of the cen-
trum anteriorly. The most marked change is seen in the
shortening of the robust diapophysis (fig. 14) which is pro-
jected more outward and less forward and its dorsal profile
is more nearly horizontal. On the dorsoventrally thickened
extremity of the diapophysis the concave facet for reception
of the tuberculum of the fourth rib is almost horizontal and
measures 42 mm. in length. At the base this transverse
process is similar to that of the preceding vertebra. The
thickened pedicle of the neural arch measures 42 mm.
Abbr.: tr., transverse process.
anteroposteriorly and the minimum transverse diameter of
the combined pedicle of the neural arch and the diapophysis
is 50 mm. Near its floor the neural canal (pl. 5, fig. 5)
measures 68 mm. transversely and although the roof is
incomplete the neural canal seems to have been wider than
high. The prezygapophysial facets are shallowly concave
and broader anteriorly than posteriorly. ‘The metapophyses
are not developed as distinct entities. The margins of the
facet (pl. 6, fig. 9) for the capitulum of the fifth rib, which is
located on the posterodorsal border of the lateral surface of
the centrum, are elevated above the adjoining surface.
Fifth Dorsal: Not represented.
Sixth Dorsal: The narrowing of the distance between the
outer margins of opposite prezygapophysial facets on the
second, third, and fourth dorsals has been rather uniform.
Hence the reduction of the same measurement to 91 mm.
on the dorsal (USNM 11976, pl. 6, fig. 5) regarded as the
sixth from the measured gap of 126 mm. on the fourth dorsal
and the 140 mm. gap on the third dorsal seems to confirm
the absence of the fifth dorsal from the series that were
excavated.
This sixth dorsal has a rather wide neural spine which
measured at least 85 mm. anteroposteriorly at the base.
The distance between the ends of opposite diapophyses is
222 mm., a marked decrease from the 258 mm. measure-
ment for the fourth dorsal. The centrum of this sixth dorsal
Ficure 14.—Anterior view of fourth dorsal, USNM 11976, of
Pelocetus calvertensis. Abbr.: tr., transverse process.
24 UNITED STATES NATIONAL MUSEUM BULLETIN 247
has slightly increased its anteroposterior diameter (73.5
mm.) and its depth anteriorly (85 mm.). The pedicles
(neurapophyses) of the neural arch continue to be massive
and relatively low in height and measure 38 mm. both
anteroposteriorly and transversely. The width (57 mm.)
of the neural canal is almost twice the vertical diameter
(30 mm.) anteriorly. The anteroposteriorly widened
diapophysis now projects outward and obliquely forward
mainly from the pedicle of the neural arch and bends upward
slightly toward its outer end. A shallow concave facet
occupies the truncated outer end of this dorsoventrally
compressed transverse process for articulation with the
tuberculum of the sixth rib. The anterior ends of both
metapophyses are broken off; the concave prezygapophysial
articular facets are extended backward beyond the anterior
margin of the neural arch and anteriorly slope rather steeply
from external to internal margins. The postzygapophysial
facets (pl. 6, fig. 10) are elongated, slope obliquely down-
ward from outer to inner margins and project backward
beyond the level of the posterior face of the centrum. As
noted for the fourth dorsal, the margins of the facet for the
capitulum of the seventh rib are elevated above the adjoin-
ing lateral surface of the centrum.
Seventh Dorsal: This dorsal (USNM 11976) exhibits a
general increase in the length (81.5 mm.) of the centrum as
well as the anteroposterior diameter of the neural arch
at the base of the neural spine. The dorsoventrally
compressed diapophysis (pl. 7, fig. 4) is bent more strongly
upward than on the sixth dorsal and the distance between
the ends of the opposite processes is 211 mm. At the
end of each diapophysis is an elongated (50+ mm.)
concave facet for tuberculum of the seventh rib. The
transverse diameter (52 mm.) continues to exceed the
vertical diameter (35 mm.) of the neural canal anteriorly.
The low pedicle of the neural arch measures 44 mm.
anteroposteriorly and 39 mm. transversely. With the
exception of the posterior 30 mm. of the right facet, both
prezygapophysial surfaces as well as both metapophyses
are destroyed on this vertebra. Viewed from the side the
neural spine is rather broad, its anterior margin more nearly
vertical than its posterior margin; the spine measures
73 mm. anteroposteriorly below its broken-off extremity.
The left postzygapophysial facet (pl. 8, fig. 3) is elongated,
slopes obliquely from outer to inner margins and projects
at least 35 mm. beyond the level of the posterior face of
the centrum. It is obvious that such projecting articular
surfaces are clasped by the prezygapophysial facets of the
following dorsal so securely that little lateral motion by
these vertebrae seems possible. The facet (pl. 9, fig. 1)
for the capitulum of the eighth rib is located on a somewhat
more prominent protuberance than on the sixth dorsal.
Eighth Dorsal: The disparity between the length (90 mm.)
of the centrum of this dorsal (USNM 11976) and the corre-
PART 1
sponding measurement (81 mm.) of the seventh dorsal is
less noticeable than the somewhat abrupt decrease in the
gap between the prezygapophysial facets. The broad
(minimum breadth, 61 mm.) dorsoventrally compressed
diapophysis (fig. 15b) projects outward and slightly upward
from the pedicle (neurapophysis) of the neural arch.
Each diapophysis differs very slightly in position from
those on the seventh dorsal, but is noticeably broader.
On the outer end of the diapophysis the horizontally
elongated (70 mm.) concave facet for the tuberculum of
the eighth rib has an arcuate upper margin. The distance
between the ends of the opposite diapophyses is 216 mm.
The left metapophysis is sufficiently preserved to show
that is was attenuated and projected considerably beyond
the level of the anterior face of the centrum. The prezy-
gapophysial facets (pl. 8, fig. 1) are deep concavities which
extend backward at least 30 mm. beyond the anterior basal
edge of the neural spine. Narrowing of the gap between
the prezygapophysial facets has become quite pronounced,
the distance between outer margins of opposite articular
facets is 62 mm. The transverse diameter (48 mm.) is
greater than the vertical diameter (35 mm.) of the neural
canal (pl. 7, fig. 2) anteriorly. The pedicles (neura-
pophyses) of the neural arch (fig. 15a) are still massive
and thick, measuring 41 mm. anteroposteriorly and 52 mm.
transversely. Although the eroded anterior border imparts
a deceptive profile, the broad neural spine (fig. 15b)
projected more upward than backward, notwithstanding
the concave curvature of its posterior edge. The elongated
(52 mm.) postzygapophysial facet on the backwardly
projecting neural arch is fairly complete on the left side
and extended at least 25 mm. beyond the level of the
posterior face of the centrum. The facet (pl. 9, fig. 2)
for the reception of the capitulum of the ninth rib has a
kidney shaped outline and is located on a prominent
protuberance on the posterodorsal angle of the lateral
face of the centrum.
Ninth Dorsal: Inasmuch as the eighth dorsal has a large
protuberant articular facet on the posterodorsal angle of the
centrum, the ninth dorsal (USNM 23058) necessarily
possessed a rib with a fairly long neck, a well developed
capitulum and a tuberculum which articulated with the
extremity of its transverse process, as well as a centrum of
equal length or slightly longer than that of the preceding
dorsal.
From the first to the eighth dorsal inclusive, the transverse
process (diapophysis) projects laterally mainly from the
thickened pedicle (neurapophysis) of the neural arch and
does not materially shift its relative position. On the ninth
dorsal (pl. 12, fig. 2), however, the markedly widened,
dorsoventrally flattened and distally upturned transverse
process (parapophysis) projects outward from the dorso-
external surface of the centrum. A rugose and excavated
A NEW WHALEBONE WHALE 25
FicURE 15.—Views of eighth dorsal, USNM 11976, of Pelocetus
calvertensis: a, anterior view; b, lateral view. Abbrs.: az., prezy-
gapophysial facet; c.f., facet for capitulum; mp., metapophysis;
pz., postzygapophysial facet; t.f., facet for tuberculum; tr.,
transverse process.
surface for the attachment of the tuberculum of the ninth
rib is present. The distance between the ends of the op-
posite transverse processes (pl. 11, fig. 1) is 290-- mm. on
this vertebra. Although both metapophyses are incomplete,
the remnants remaining show that they projected forward
beyond the level of the anterior face of the centrum; the gap
between them is quite narrow. The prezygapophysial
facets were obviously greatly reduced in size. The trans-
verse diameter (56 mm.) is greater than the vertical
diameter (48 mm.) of the neural canal anteriorly.
The pedicles of the neural canal measure 67 mm. antero-
posteriorly, but are quite thin. The broad neural spine
(pl. 11, fig. 1), truncated abruptly distally, projects more
upward than backward, and rises 147 mm. above the roof
of the neural arch. The backwardly projecting dorsal
portion of the neural arch is eroded and seemingly did not
possess postzygapophysial articular surfaces although
it extended beyond the level of the posterior face of the
centrum.
The length of the centrum (104 mm.) is less than its
transverse diameter (118.5 mm.) anteriorly. The outline of
the anterior end of the centrum (pl. 12, fig. 2) continues to
be subcordate, flattened dorsally. No facet for the capitu-
lum of the following rib exists either anteriorly or posteriorly
on the lateral surface of the centrum.
Ten Dorsal: The tenth dorsal (USNM 11976) associated
with the skull, aside from small excrescences on the centrum,
shows the effects of spondylitis deformans mainly in the
deformation of the extremity of the transverse processes.
Each transverse process (minimum width, 68 mm.) is
inclined slightly upward toward its outer end which bears a
deep horizontal depression (pl. 9, fig. 3) for articulation with
the head of the corresponding rib. The distance (262 mm.)
between the ends of the opposite transverse processes
(pl. 8, fig. 2) is much greater than on the eighth dorsal
(USNM 11976) and the neural canal (fig. 16a) has dimin-
ished in width (42 mm.) and in height (32 mm.) anteriorly.
The pedicle of the neural arch has become quite thin
(minimum thickness, 15 mm.) and widened antero-
posteriorly (60 mm.). Although largely destroyed on this
dorsal, the metapophyses (pl. 8, fig. 2) were compressed
from side to side and their dorsal edge has its origin some
33 mm. behind the notch or gap between the prezygapo-
physial facets.
facets are preserved; on both sides they are usually narrow
and are separated by a small U-shaped notch (width, 17
mm.). The postzygapophysial facets (fig. 16b) are destroyed
as is the backwardly projecting dorsal portion of the neural
arch. The broad neural spine (fig. 16b) is relatively high,
rising 197 mm. above the roof of the neural canal and slant-
ing slightly backward. Unfortunately, the anterior and
posterior edges of the neural spine are eroded.
Only remnants of the prezygapophysial
26 UNITED STATES NATIONAL MUSEUM BULLETIN 247
The centrum of the tenth dorsal (USNM 23058) in the
referred vertebral series is slightly larger (length, 110 mm.)
than the preceding (length, 103.5 mm.). Although fully
adult (pl. 12, fig. 1), both epiphyses being ankylosed to the
centrum, no malformation is present. The outline of the
anterior end of the centrum is subcordate, flattened dorsally,
and the lateral surfaces are deeply concave. On the right
side, the transverse process (pl. 11, fig. 2) is complete;
it is more noticeably widened (minimum width, 63 mm.)
and expanded distally (96 mm.) than that of the preceding
vertebra. The elongated but narrow extremity of this
process is roughened for the attachment of the head of the
tenth rib. The width (46 mm.) and height (45 mm.) of
the neural canal anteriorly are approximately equal. The
pedicle of the neural canal is very thin (7 mm.), but measures
67 mm. anteroposteriorly.
Eleventh Dorsal: This dorsal (USNM 11976) is noticeably
malformed in consequence of spondylitis deformans.
Longer transverse processes (parapophyses) with increased
horizontal enlargement, slightly longer centrum, and a
narrower neural canal distinguish this dorsal (pl. 7, fig. 3)
from the preceding vertebra. Although a_ perceptible
increase in the length (107 mm.) of the centrum is observ-
able, the width (120 mm.) of its posterior face as compared
to the width (112 mm.) of the anterior face has not been
materially altered. The distance (312 mm.) between the
ends of the opposite transverse processes (pl. 8, fig. 4) is
considerably greater than that of the preceding dorsal.
Each transverse process (parapophysis) projects outward
from the upper portion of the lateral surface of the centrum
below the level of the base of the neural arch and at a lower
level than on the preceding dorsal. Each parapophysis is
compressed dorsoventrally (right, minimum anteroposterior
diameter, 56 mm.) and is expanded horizontally distally
and also thickened to provide an increased area for the
attachment of the singleheaded rib. The minimum antero-
posterior diameter (62 mm.) of the laterally compressed
pedicle of the neural arch does not differ materially from
the corresponding measurement (60 mm.) of the preceding
vertebra. The neural canal anteriorly is slightly higher
(39 mm.) than wide (38 mm.). The extremities of both
metapophyses are broken off as well as the prezygapophysial
facets, if present. The backwardly projecting dorsal portion
of the neural arch is likewise missing. An abnormal devel-
opment of a large osseous projection (pl. 9, fig. 4) on the
posterior half of the ventral face of the centrum has resulted
in an unusual malformation of this vertebra.
This vertebra (USNM 23058) is represented in the referred
series. The outline of the anterior end of the centrum (pl.
12, fig. 3) is less noticeably subcordate, and the lateral
surfaces remain deeply concave. This vertebra is charac-
terized in part by the wide transverse processes (minimum
width, 65 mm.) which are strongly expanded distally
PART 1
ra SCA Re
aN NN \\
A\\
ens
a \
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cS A i) }
SS)
(|
(
WE
FicurRE 16.—Views of tenth dorsal, USNM 11976, of Pelocetus
calvertensis: a, anterior view; b, lateral view. Abbrs.: c.f., facet
for capitulum; mp., metapophysis; tr., transverse process.
A NEW WHALEBONE WHALE 27
USNM 11976—Dorsal Vertebrae: Dir D.2
Anteroposterior diameter of centrum 41.5 47-5
Transverse diameter of centrum anteriorly 112 118
Vertical diameter of centrum anteriorly QI 84.
Tip of neural spine to ventral face of = =
centrum
Minimum anteroposterior diameter of — 26
pedicle of neural arch
Transverse diameter of neural canal 80 82
Distance between ends of diapophyses = 254+
Distance between ends of transverse = =
processes
Dorsal face of metapophysis to ventral — 103
face of centrum
(width, 106 mm.). The anterior one-half of the extremity
of this process is quite thin, markedly compressed dorso-
ventrally in contrast to the thickened posterior 50 mm. of the
articular end which attains a maximum thickness of 24 mm.,
to which is attached the head of the corresponding rib. The
distance (375 mm.) between the ends of the opposite trans-
verse processes (pl. 11, fig. 3) is considerably greater than
that of the preceding dorsal in the referred series. The
minimum anteroposterior diameter (70 mm.) of the laterally
compressed pedicle of the neural arch represents a slight
increase over that of the preceding dorsal. The height
and width of the neural canal anteriorly are approximately
equal (45 mm.). The neural spine has increased slightly in
height, but no postzygapophysial facets are developed on
the backwardly projecting dorsal portion of the neural arch.
This backward slanting neural spine (pl. 11, fig. 7) is broad,
its posterior profile convex, and its anterior profile more
nearly straight. Presumably this neural spine was truncated
at its extremity in conformity with that of the twelfth dorsal.
Twelfth Dorsal: The occurrence of a twelfth rib among
the ribs associated with the skeletal remains (USNM 11976)
justifies the inclusion of a twelfth dorsal in this series of
vertebrae, although this vertebra was not included among
those associated with the skull.
The twelfth dorsal (USNM 23058) of the referred series
is the largest of the thoracic vertebrae and possesses the
highest neural spine (pl. 11, fig. 8) and the longest trans-
verse processes. The distance (436 mm.) between the
ends of the opposite broad transverse processes (pl. 11,
USNM 23058—Dorsal Vertebrae:
Anteroposterior diameter of centrum
Transverse diameter of centrum anteriorly
Vertical diameter of centrum anteriorly
Tip of neural spine to ventral face of centrum
Minimum anteroposterior diameter of pedicle of neural arch
Transverse diameter of neural canal
Distance between ends of transverse processes
Dorsal face of metapophysis to ventral face of centrum
D3 = D.4 D6 D.7 D.8 D.to— Durr
58 67 73-5 81 go 103.5 107
II7 115 113.5 III. 5 110.5 112 112
80 83 84 85 86 93 90
—— = 176+ 248+ 2098 313 =
35 «41 40 45 51 62.5 62
75 68 57 54 53 42 38
292 258 222 QrI 216 — —
— = = = = 262 312
110. ~—-:106 107 = 131 134+ —
fig. 4) has increased over that of the preceding dorsal,
although the roughened extremity of the process is narrower
(79 mm.) and not quite so thick (20 mm.). Nevertheless,
the area for the cartilaginous attachment of the twelfth
rib may have been restricted to the posterior half of this
extremity. Both transverse processes project outward
nearly horizontally.
The width and height of the neural canal anteriorly
are equal (42 mm.). The pedicles of the neural arch are
thin and measure approximately 74 mm. anteroposteriorly.
Both metapophyses are incomplete, but the left process is
sufficiently preserved to show that it projected forward
beyond the level of the anterior face of the centrum.
The gap between the opposite metapophyses is narrow
and may have been adequate for clasping the backwardly
projecting portion of the neural arch and base of the neural
spine. The broad neural spine (pl. 11, fig. 8) is inclined
backward, truncated abruptly at its extremity and rises
170 mm. above the roof of the neural canal.
The outline of the anterior end of the centrum (pl. 12,
fig. 4) is more ovate than subcordate, and the lateral sur-
faces diameter
(124 mm.) of the posterior end of the centrum exceeds
very slightly that (121 mm.) of the anterior end.
Measurements (in mm.) of dorsal vertebrae of USNM
11976 are tabulated above.
Measurements (in mm.) of dorsal vertebrae of USNM
23058 are tabulated below.
are deeply concave. The transverse
D.9 D.10 D.rr D.12
104 110 114 119
118.5 118.5 121 122
96 98 98. 5 102
285 292 + 302 + 324
67 67 7° 74
56 46 45 42
290+ 345+ 375 436
155 158-4 168+ 165 +
28 UNITED STATES NATIONAL MUSEUM BULLETIN 247
LUMBAR VERTEBRAE.—Eight lumbar vertebrae (USNM
11976) were associated with the skeleton of this cetothere,
although for one only the neural spine was recovered.
The epiphyses are ankylosed to the centra of all the
lumbars. Five consecutive lumbars (fig. 19) are firmly
bound together by an advanced stage of spondylitis
deformans or osteophytosis (Tobin and Stewart, 1952, p.
407), the ankylosed osseous outgrowths protruding ventrally
in a continuous band along the under side of these centra.
The ossification of the longitudinal ligaments of this portion
of the vertebral column and this bony bridging effectively
prevented spinal motion during life. When arranged in
serial sequence the centra in this series progressively
increase in length, which exceeds slightly their width,
respectively, although the true measurement is masked by
this external exostosis. The usual ventral longitudinal
keel or carina is malformed by bony excrescences. The
dorsoventrally compressed transverse processes (para-
pophyses) are widened beyond the middle of their length
and possess rounded distal ends. These transverse processes
decrease in length from the fourth to the ninth in the series.
The neural canals are higher than wide anteriorly and
decrease in width from the second to the ninth. Neither
pre- nor post-zygapophysial facets are developed on these
lumbars. The elongated thin lamina-like metapophyses
are large, well-developed processes that project upward and
forward from the neural arch and are also inclined obliquely
outward from ventral to dorsal edges. They do not embrace
tightly the rather narrow backwardly projecting dorsal
portion of the neural arch of the preceding vertebra which
on the anterior lumbars extends slightly beyond the level
of the posterior face of the centrum. The opposite meta-
pophyses are separated ventrally in front of the base of the
neural spine by a gap varying from 20 mm. to 30 mm.
Viewed from the side, the neural spines are relatively
broad and high, and are inclined slightly backward.
Either the anterodistal or the posterodistal angle of the
neural spine may project beyond the general inclination
of the corresponding edge.
A smaller lumbar vertebra (length of centrum, 106 mm.;
transverse diameter anteriorly, 105.5 mm.), with some-
what shorter and narrower transverse processes, fortuitously
associated with the skeletal remains (USNM 11976) is
referred to another Calvert cetothere.
Seven consecutive lumbar vertebrae (USNM 23058) of a
fully mature individual, all epiphyses being firmly ankylosed
to the centra, are included in the vertebral series of this
referred specimen, which supplements the skeletal material
obtained in 1929. The usual longitudinal keel or carina
is not developed on the ventral face of the centra of the
anterior four of these vertebrae, although it is faintly
indicated on the third (or fourth); it is quite distinct on the
fifth, sixth, and seventh lumbars. No vestige of an area for
PART 1
possible cartilaginous attachment of the head of a rib is
discernible on the extremities of the transverse processes of
these four anterior vertebrae here referred to the lumbar
series. Inasmuch as these seven lumbars were excavated in
their natural sequence following the four posteriormost
dorsals, the descriptions that follow will be based primarily
on them. No indication of malformation resulting from
occurrence of spondylitis deformans was observed on any of
the seven vertebrae. The lumbars of USNM 11976 will be
allocated to their assumed position in the normal sequence.
First Lumbar: It is apparent that the first lumbar is
not represented among the lumbars of USNM 11976
inasmuch as none of them seem to meet the structural
requirements of the first vertebra in this portion of the
vertebral column. It seems to be the general rule among
mysticetes that the anteroposterior diameter of the pedicle
of the neural arch of the first lumbar is gradually and not
abruptly increased over that of the posterior dorsal
vertebrae.
The most obvious alteration in anterior lumbars is the
progressive dorsoventral compression of the transverse
process (parapophysis) which contines to project outward
from the external face of the centrum at approximately
the same level as on the twelfth dorsal. The absence of
an attached rib-end eliminates any necessity for a thickening
of this process.
The first lumbar (USNM 23058) of the referred series
has a slightly longer (122 mm.) centrum than the twelfth
dorsal, and the distance (480 -- mm.) between the ends of
the opposite transverse processes has increased noticeably.
The right transverse process (pl. 13, fig. 1) is incomplete;
the distal half of the anterior border as well as the extremity
of the left process are eroded, and consequently the present
oblique truncation may not be accurately shown. Except
for the basal portions of the pedicles, the neural arch, the
neural spine and the metapophyses were missing when
this vertebra was excavated. The pedicles of the neural
arch extend more than three-fourths of the length of the
centrum. The transverse diameter of the neural canal
anteriorly is 44 mm.
The outline of the anterior face of the centrum is more
nearly circular (though flattened dorsally) than subcordate.
The lateral and ventral surfaces are deeply concave and
no ventral longitudinal carina or keel is visible. A low
longitudinal ridge is present on floor of the neural canal.
Second Lumbar: This vertebra (USNM 23058) in the
referred series was not completely preserved when found.
All of the neural arch except the basal portions of its
pedicles and the lower half of the neural spine were not
preserved, although the basal portions of both metapophyses
were found. The centrum of this lumbar is slightly longer
(125 mm.) than the first lumbar and the outline of the
anterior end is quite similar. The lateral and ventral
A NEW WHALEBONE WHALE 29
surfaces of the centrum are deeply concave; no median
longitudinal ventral keel is developed and no visible
longitudinal ridge is present on the floor of the neural
canal.
Portions of both dorsoventrally compressed transverse
processes (pl. 13, fig. 2) are missing. The borders of the
right process are sufficiently complete to indicate that the
distal end was not widened perceptibly. This process
resembles that of the first lumbar in being somewhat
narrower than those of the succeeding lumbars.
The base of the thin right pedicle of the neural arch
occupies slightly more than two-thirds of the length of the
centrum. The neural spine (pl. 13, fig. 6) apparently
had not noticeably increased in width; the distal extremity
is strongly truncated.
Third Lumbar: ‘The third lumbar in the referred series
(USNM 23058) is the first to exhibit the tendency toward a
distal widening of the transverse process. For this reason,
the anterior lumbar (USNM 11976) whose transverse
process (pl. 10, fig. 1) is noticeably compressed dorso-
ventrally, widened beyond the middle of its length, and
rounded at the extremity is regarded as the third. The
anterior margin of this process is convexly curved, but its
posterior edge is more nearly straight. The distance be-
tween the ends of the opposite transverse processes is 440
mm. The pedicles (neurapophyses) of the neural arch are
compressed from side to side, extend more than half the
length of the centrum, and measure anteroposteriorly 67
mm. (minimum). The neural canal (fig. 17a) anteriorly is
higher (40 mm.) than wide (35 mm.). A strong median
longitudinal ridge extended the length of the floor of the
neural canal. Neither pre- nor postzygapophysial facets
are present. Although both metapophyses (fig. 17b) are
broken off, their basal remnants show that they were com-
pressed from side to side and project upward and forward
from the neural arch beyond the level of the anterior face of
the centrum. The broad neural spine projects upward
162+ mm. above the roof of the neural canal and is in-
clined backward. ‘The anterior border of the neural spine
is, however, incomplete, particularly the anterodistal angle.
The centrum of this lumbar is longer (116 mm.) and
slightly wider (114 mm.) than the tenth dorsal (correspond-
ing measurements, 107 and 112 mm.). The usual ventral
longitudinal keel on the centrum, if originally present, has
been obliterated by exostosis, which has resulted in the
formation of a rather large osseous protuberance on the
posterior end of the ventral surface.
The third lumbar in the referred series (USNM 23058)
has a narrow (39 mm.) and high (47 mm.) neural canal,
and the pedicles of the neural arch occupy almost 68 per-
cent of the length of the centrum. Although the extremities
of both metapophyses are missing, the preserved remnants
project forward beyond the level of the anterior end of the
75599965 —3
centrum. The backward projecting dorsal portion of the
neural arch and the adjoining basal portion of the neural
spine are broken off. The thin backward slanting neural
spine (pl. 13, fig. 7) projects 188 mm. above the roof of the
neural canal.
The outline of the anterior end of the centrum is similar to
that of the second lumbar, the lateral surfaces are deeply
concave, and a low rounded ventral longitudinal keel is
discernible. Each dorsoventrally compressed transverse
process (pl. 13, fig. 3) projects outward from the lateral
surface of the centrum but is bent forward to such an ex-
tent that its anterodistal angle extends forward beyond the
level of the anterior face of the centrum.
Fourth Lumbar: The shape, dimensions, and backward
inclination of the detached neural spine (USNM 11976,
pl. 10, fig. 3) conform to the anticipated general character-
istics of the fourth in the lumbar series. This rather broad
(anteroposterior diameter at base, 96 mm.) neural spine
projects upward 205 mm. above the roof of the neural canal
and is obliquely truncated at its extremity. Both anterior
and posterior edges are slightly curved; the anterodistal
angle is prominent and projects forward. Both meta-
pophyses are broken off at the base, but originate in the
same relative position as on the second lumbar, although
the internal gap between them (37 mm.) seems to be
reduced.
On the fourth lumbar of the referred series (USNM 23058)
the dimensions of the neural canal are approximately the
same as those of the third lumbar. The thin pedicles of the
neural arch occupy 67 percent of the length of the centrum.
The left metapophysis although eroded projects forward
beyond the level of the anterior end of the centrum and
presumably clasped the backwardly projecting basal
portion of the neural spine of the preceding lumbar. The
dorsal portion of the neural arch is incomplete on both
sides. The width of the backward slanting neural spine
(pl. 13, fig. 8) is approximately the same as that of the
preceding lumbar and the distal endis rounded. The neural
spine projects 194 mm. above the roof of the neural canal.
On the right side the transverse process (pl. 13, fig. 4)
is broken off near its base; on the left side the anterior and
posterior borders of this process are missing. This trans-
verse process is strongly inclined forward and its distal
end is rounded.
Fifth Lumbar: Longer transverse processes, higher neural
spine, narrower neural canal, and more robust meta-
pophyses distinguish this lumbar from the third in this
series (USNM 11976). The broad (minimum diameter,
68 mm.) transverse processes (pl. 10, fig. 2) are directed
outward and slightly forward, and noticeably increase in
width toward their extremities. The distance between
the ends of the opposite transverse processes is 470 mm.
The anterior edge of each process is more strongly curved
30 UNITED STATES NATIONAL MUSEUM BULLETIN 247 PART 1
Ficure 17.—Views of third lumbar, USNM 11976, of Pelocetus
calvertensis: a, anterior view; 5, lateral view. Abbrs.: mp., meta-
pophysis; tr., transverse process.
NY
A NEW WHALEBONE WHALE 31
HEY)
Wy y] / iy) /) y]
i Mi /; )
ij H))
Ficure 18.—Views of fifth lumbar, USNM 11976, of Pelocetus
calvertensis: a, anterior view; 6, lateral view. Abbrs.: mp., meta-
pophysis; tr., transverse process.
Nf
755—999—_65——4
32 UNITED STATES NATIONAL MUSEUM BULLETIN 247
than the posterior. The pedicles of the neural arch do not
differ materially from those of the third lumbar (minimum
anteroposterior diameter, 71 mm.). The neural canal
(fig. 18a) anteriorly is higher (36 mm.) than wide (32 mm.)
and a strong median longitudinal carina between rather
deep paralleling grooves extends the length of the floor of
the neural canal.
No vestige exists of either pre- or postzygapophysial
facets. The backwardly projecting dorsal portion of the
neural arch (fig. 18b) projects very little if at all beyond the
level of the posterior face of the centrum, and obviously
could not have been firmly clasped by the metapophyses
of the next lumbar. The elongated lamina-like meta-
pophyses (pl. 10, fig. 2) are large, rather thick transversely
(13 mm.), and project upward and forward at least 30 mm.
beyond the level of the anterior face of the centrum.
The opposite metapophyses diverge slightly.
The neural spine (fig. 18b) is wider (103 mm.) antero-
posteriorly at the base than that of the third lumbar,
inclined noticeably backward, and projects upward 232
mm. above the level of the roof of the neural canal; its
anterior edge is slightly curved and its posterior edge
nearly straight.
Although the diameters of the anterior and posterior
ends of the centrum of this vertebra are not materially
different from those of the third lumbar, the centrum is
longer (121.5 mm.). Bony excrescences are attached on
all sides around the posterior end of the centrum.
On the fifth lumbar (pl. 14, fig. 5) of the referred series
(USNM 23058) the anteroposterior diameter of the neural
spine has increased and its extremity is abruptly truncated.
The neural spine rises 190 mm. above the roof of the neural
canal. Little if any change in the dimensions of the neural
canal are visible, the width (35 mm.) and the highth
(40 mm.) do not differ materially from the preceding lum-
bar. The thin pedicles of the neural arch occupy 71
percent of the length of the centrum. On the left side the
metapophysis although slightly eroded projects forward
beyond the level of the anterior face of the centrum.
Anteriorly the transverse diameter (124 mm.) of the
circular end of the centrum exceeds the vertical diameter
(112.5 mm.). The lateral surfaces of the centrum are
deeply concave and the low, rounded longitudinal ventral
keel is depressed medially. A decrease in the distance
(482 mm.) between the ends of the opposite transverse
processes (pl. 14, fig. 1) presumably commenced with this
lumbar, although the distance (360 mm.) between the tip
of the neural spine and the ventral face of the centrum
Each
transverse process is directed outward, but more strongly
inclined forward than on the fourth lumbar. The ex-
tremity of this process is rounded.
increases on the sixth and seventh lumbars at least.
PART 1
Sixth Lumbar: The sixth lumbar (pl. 14, fig. 6) in the
referred series (USNM 23058) lacks most of the dorsal
portion of the neural arch and the metapophyses. The
highth (47 mm.) of the neural canal has increased, but
only a very minor decrease in the width (34 mm.) is
observable. The pedicles of the neural arch occupy 69
percent of the length of the centrum. No visible median
longitudinal ridge is present on the floor of the neural
canal. The broad, backward slanting and squarely
truncated neural spine rises 203 mm. above the roof of the
neural canal. Unfortunately, the posterobasal portion of
the neural spine is missing.
A slight increase in the length (136.5 mm.) of the centrum
is accompanied by a minor decrease (120 mm.) in the
width of the circular anterior face. The lateral faces of the
centrum are deeply concave and the lower rounded
ventral longitudinal keel is a little more prominent. Each
transverse process (pl. 14, fig. 2) projects outward and
slightly forward from the lateral surface of the centrum
and is slightly widened beyond the middle of its length,
but beyond that point the anterior and posterior edges
curve toward the bluntly rounded extremity. The ex-
tremity of each transverse process extends forward beyond
the level of the anterior end of the centrum.
Seventh Lumbar: This lumbar (pl. 14, fig. 7) is the
largest vertebra in the referred series (USNM 23058).
Although the posterior portion of the neural arch was not
preserved, the anterior portion was continuous with the
neural spine. On the right side the remaining portion of
the metapophysis does not project forward beyond the
level of the anterior end of the centrum. The broad neural
spine exhibits a concavely curved anterior profile, a
convexly curved posterior profile, and a rounded extremity.
This neural spine rises 210 mm. above the roof of the neural
canal. The thin pedicles of the neural arch occupy 68 per-
cent of the length of the centrum. No obvious change is
observable in the width (34 mm.) and the highth (50 mm.)
of the neural canal anteriorly. No median longitudinal
ridge is present on the floor of the neural canal.
The width (121 mm.) and the height (109 mm.) of the
circular anterior end of the centrum are essentially the
same as for the sixth lumbar. A more obvious rounded
ventral longitudinal keel is developed on the centrum,
but no material change is observable in the concaveness of
the lateral surfaces. The transverse processes (pl. 14,
fig. 3) project outward and forward from the lateral
surface of the centrum at the same level as on the sixth
lumbar, although the rounded distal ends do not extend
as far forward beyond the level of the anterior end.
Sixth, Seventh, Eighth, Ninth, and Tenth Lumbars: These
five firmly ankylosed consecutive lumbar vertebrae (fig.
19) possess long, anteroposteriorly widened and_back-
wardly inclined neural spines that decrease slightly in
A NEW WHALEBONE WHALE 33
a.
| (
il
His
AN le
)
ill}
Hii if, Ze
il HH
C
ss
=
Figure 19.—Lateral views of ankylosed lumbar vertebrae, USNM
11976, of Pelocetus calvertensis: a, sixth lumbar; b, seventh lumbar;
¢, eighth lumbar; d, ninth lumbar; e, tenth lumbar.
height toward the hinder end of the series and are not uni-
form in width. The minimum anteroposterior diameter
(110 mm.) of the neural spine of the tenth lumbar exceeds
the corresponding measurement (95 mm.) of the sixth lum-
bar. Variable profiles are displayed when the neural spines
are viewed from the side, the terminal end being rounded
on the sixth and obliquely truncated on the ninth.
The metapophyses of the sixth lumbar are longer, broader
and thicker than on the succeeding vertebrae, those of the
tenth being rather slender. The backwardly projecting
dorsal portion of the neural arch on these lumbars does not
extend far enough beyond the level of the posterior end of
the centrum to be tightly embraced by the metapophyses of
the next vertebra, except in the case of the seventh which is
thrust back against the base of the eighth’s neural spine and
fused with it for a depth of 60 mm. ‘Toward the hinder
end of this series of consecutive lumbars the metapophyses
tend to approximate their opposites more closely and their
anterior ends become slightly more elevated. On all five
lumbars the metapophyses project forward beyond the level
of the anterior end of the centrum.
An increase in the anteroposterior diameter of the cen-
trum is observable from the sixth (120 mm.) to the tenth
(137 mm.) as well as the width.
The neural canal is progressively reduced in width to
26 mm. on the tenth lumbar. The median longitudinal
ridge on the floor of the neural canal is markedly reduced
on the tenth lumbar. The pedicles (neurapophyses) of the
neural arch are all compressed from side to side, but vary
in minimum anteroposterior diameter from 78 mm. (sixth
lumbar) to 70 mm. (eighth lumbar).
From the anterior to the posterior end of this series of five
lumbars the broad and rather thin transverse processes
decrease in length as well as in breadth on the distal half,
but very slightly in relative position and direction. The
distance between the ends of opposite transverse processes
decreases from more than 420 mm. (sixth lumbar) to 365
mm. (tenth lumbar).
As mentioned previously this whale was a mature indi-
vidual which displayed a far advanced stage of osteophy-
tosis. A continuous thick irregular osseous band extends
the entire length of the ventral aspect of these five consecu-
34 UNITED STATES NATIONAL MUSEUM BULLETIN 247 PART 1
USNM 11976—Lumbar Vertebrae: L.3 Te L.6 L.7 Lg L.9 L.10
Anteroposterior diameter of centrum 116 121.5 120 120 132 131 137
Transverse diameter of centrum anteriorly 105.5 115.5 115.5 120 = = —
Vertical diameter of centrum anteriorly 93 96 98 = = = 130
Tip of neural spine to ventral face of centrum 317 370 360+ 375 380 395 400
Minimum anteroposterior diameter of pedicle of 68.5 71 78 74 7o 71 74
neural arch
Transverse diameter of neural canal 35 31 29 30 30 37 33
Distance between ends of transverse processes 440 470 420+ 405+ 360+ 325+ 365
Dorsal face of metapophysis to ventral face of 154.5 177 180 — = = 190
centrum
tive lumbars and projects also beyond the anterior end of
the sixth and the posterior end of the tenth lumbar. The
centra of the sixth, seventh, eighth, and ninth lumbars are
completely ankylosed on the left side by an osseous bridging.
On the left side a narrow gap separates the centra of the
sixth and seventh as well as the seventh and eighth. Except
at the ventral border and on the right side, the centra of the
ninth and tenth lumbars are not in contact with each other.
Posterior Lumbar: A somewhat larger lumbar vertebra
(USNM 23056) with fully ankylosed epiphyses has similarly
elongated transverse processes, high neural spine, thin
lamina-like metapophyses (directed more strongly upward)
and rather high neural canal (60 mm.). The measurements
of this lumbar are as follows: length of centrum, 154 mm.;
width of centrum anteriorly, 128 mm.; and vertical height
of centrum anteriorly, 118 mm. The dimensions of this
lumbar indicate that this Miocene cetothere may possibly
attain a length of 25 feet, assuming that the remainder of
the skeleton shows a similar increase. The estimated length
of the skeleton (USNM 11976) herein described is about 22
feet of which the lumbar series (i.e., 12 vertebrae) seemingly
measured 1580 mm. (62 inches) as compared to possibly
1900 mm. (75 inches) for this larger individual.
Measurements (in mm.) of lumbar vertebrae of USNM
11976 are tabulated above.
Measurements (in mm.) of lumbar vertebrae of USNM
23058 are tabulated below.
CAUDAL VERTEBRAE.—At least one (pl. 10, fig. 4) of the
caudal vertebrae associated with the skeleton (USNM
11976) belongs to another smaller cetothere and probably
is referable to the same skeleton as the small lumbar vertebra
heretofore mentioned. The two small terminal caudals are,
however, tentatively referred to Pelocetus. Five caudal
vertebrae (USNM 23059) found associated with an atlas,
three dorsals, one lumbar and other skeletal elements of
Pelocetus furnish a minimum of information regarding the
caudal series.
Anterior Caudal: In view of the development of the
posterior haemal tubercles (haemapophyses), the posterior
widening of the centrum, and the large thickened meta-
pophyses, the largest caudal vertebra (USNM 23059) is
regarded as the third or fourth in the caudal series. These
posterior haemal tubercles attain their largest size on the
third caudal of Megaptera.
The largest and most anteriorly situated of these five
caudals (pl. 14, fig. 4) lacks portions of the transverse
processes, the right metapophysis and the neural spine.
The anterior caudals of these Calvert cetotheres usually are
characterized by an enlargement of the posterior end of the
centrum, resulting from the development of the posterior
haemal tubercles. The transverse diameter posteriorly
(160 mm.) of this caudal exceeds that (153 mm.) of the
anterior end. The metapophyses are noticeably thickened,
bent upward and outward, and do not project beyond the
level of the anterior end of the centrum and hence did not
clasp the base of the neural spine of the preceding caudal.
USNM_ 23058— Lumbar Vertebrae: LI
Anteroposterior diameter of centrum 122
Transverse diameter of centrum anteriorly 118
Vertical diameter of centrum anteriorly 103. 5
Tip of neural spine to ventral face of centrum 325+
Minimum anteroposterior diameter of pedicle of 81
neural arch
Distance between ends of transverse processes
Dorsal face of metapophysis to ventral face of
centrum
L.2 L.3 L.4 L5 L.6 L.7
125 127 130 132.5 136. 5 139
118 121 125 124 120 121
104 108 108 112.5 110 109
330+ 353 3484 360 363 375
80+ 75 75+ 82+ 84+ 80
475+ 492 = 482 463 445
175+ 182+ 178 180 182+ 192
A NEW WHALEBONE WHALE 35
The neural spine presumably was rather short, judging
from its posterior location on the roof of the neural arch.
This condition may be taken as an indication of the rapid
diminution of the neural spines of the anterior caudals.
The height (32 mm.) exceeds slightly twice the width
(15 mm.) of the neural canal anteriorly.
The massive centrum (pl. 14, fig. 8), which measures 162
mm. anteroposteriorly, is noticeably depressed or hollowed
out above and below the transverse processes. The anterior
boarder and extremity of the right transverse process (pl.
14, fig. 4) is missing and the left process is broken off at the
base. Both processes were broad at the base which occupies
more than half the length of the centrum. On the four or
five anterior caudals of some recent mysticetes the seg-
mented blood vessels do not follow their upward course on
the centrum in well defined grooves. On this Calvert
caudal, however, these blood vessels obviously traversed a
broad shallow groove which is directed obliquely upward
and backward, commencing in front of the transverse
process, to the posterior end of the neural canal. On the
ventral surface of the centrum the anterior haemal tubercles
although partially eroded are smaller and less protuberant
than the large posterior pair which are also eroded. Medi-
ally between these haemal tubercles is the broad shallow
groove or haemal canal which transmits the caudal artery
and caudal vein.
Posterior Caudals: The four small terminal caudals
(USNM 23059) were located posterior to the last caudal
which has the neural canal inclosed by the neural arch.
The smaller Calvert cetothere (USNM 16667) has six
caudals of this type. The anterior end of the largest
(pl. 15, fig. 1) of these four caudals is higher (117 mm.)
than wide (106 mm.). The posterior end of the centrum
is slightly convex and the anterior end is flattened. There
is an obvious tendency in these posterior caudals for the
posterior end of the centrum to become smaller than the
anterior as well as more convex. The centrum is pierced
dorsoventrally by two large vascular canals, which are
closely approximated dorsally and open into a deep
longitudinally elongated pit, bounded on each side by
vestiges of the pedicles of the neural arch; the ventral
orifices are located on the portion of the centrum that is
missing. The vertical vascular canals that pierce the
centra in the posterior caudal region of Recent mysticetes
permit communication of the branches of the caudal
artery and caudal vein between the ventral haemal groove
and the dorsal neural canal.
A less noticeable difference exists between the width
(108 mm.) and the height (101 mm.) of the anterior face
of the next largest caudal (USNM 23059). The anterior
end (pl. 15, fig. 2) while flattened is depressed medially
and the posterior end is convex. The vertical vascular
canals open dorsally into a fairly deep longitudinal ovoidal
cavity. As regards the three ventral orifices of these vas-
cular canals, the outer ones are separated from the median
orifice by an interval of approximately 30 mm.
The third of these posterior caudals (USNM 23059)
is wider (64 mm.) than high (55 mm.), its flattened an-
terior end (pl. 15, fig. 3) is depressed medially as is its
more rounded posterior end. The two vertical vascular
canals open dorsally into a rather small transversely oval
cavity. On the flattened ventral face of the centrum the
three orifices of these canals are larger than the dorsal
orifices. Both sides of the centrum are deeply grooved
longitudinally about the middle of their highth.
The smallest of these (USNM 23059) posterior caudals
(pl. 15, fig. 4) has the flattened anterior end depressed
medially; the more rounded posterior end is seemingly
slightly eroded. The outline of this caudal is quadrangular,
its lateral surfaces being irregularly grooved longitudinally
about the middle of their height. The two dorsal orifices
of the vascular canals open into a transverse and somewhat
elliptical cavity, but there are only two ventral orifices
separated by an interval of 21 mm.
Ficure 20.—Anterior view of posterior caudal, USNM 11976,
of Pelocetus calvertensis.
The largest of the two posterior caudals associated with
the skeletal remains (USNM 11976) is almost quadrangular
in outline when viewed from in front (fig. 20). Both sides
of the centrum are broadly grooved longitudinally near the
middle of their height. The centrum is pierced dorso-
ventrally by two large vascular canals which are closely
approximated dorsally and rather widely separated
ventrally (32 mm.). Between the ventral orifices of these
two canals are two fairly deep blind pits of similar dimen-
sions (pl. 5, fig. 6). The anterior end of the centrum is
concave in contrast to the less depressed posterior surface.
The measurements of this caudal are as follows: greatest
thickness of centrum, 42 mm.; height of centrum anteriorly,
57 mm.; breadth of centrum anteriorly, 68 mm.; height
of centrum posteriorly, 62 mm.; and breadth of centrum
posteriorly, 71 mm.
More than half of the very small porous terminal caudal
(USNM 11976) is missing. The direction of the two
dorsoventral vascular canals indicates that their orifices
were more widely separated ventrally (15 mm.) than
dorsally. All surfaces of the centrum are strongly rugose,
and the greatest thickness is 25 mm.
36 UNITED STATES NATIONAL MUSEUM BULLETIN 247
DoS
a)
PART 1
FicurRE 21.—Views of left scapula, with restored anterior and vertebral borders, USNM 11976,
of Pelocetus calvertensis: a, external view of left scapula; 6, view of glenoid articular cavity of
left scapula. Abbr.: c.pr., coracoid process.
Measurements (in mm.) of the caudal vertebrae of USNM
23059 are as follows:
Anteroposterior diameter of centrum
Transverse diameter of centrum anteriorly
Vertical diameter of centrum anteriorly
Transverse diameter of neural canal
Distance between ends of transverse processes
Dorsal face of metapophysis to ventral face of centrum
Fore Limb
The shoulder blade is represented by a nearly complete
left scapula and the anterior and basal portions of the right.
The right and left humeri and the right and left radii are
unusually well preserved. The distal 220 mm. of the left
ulna also was recovered during the excavation of the skele-
ton (USNM 11976). The upper portion of the fore limb,
comprising the scapula, humerus and radius, measured at
least 39 inches (990 mm.) in length. Eleven carpal bones,
nine metacarpals and nine phalanges were associated with
the limb bones. Judging from the shape of the individual
Second Third Fourth
Ant. Post. Post. Post. Post.
Ca. Ca. Ca. Ca. Ca.
162 86 65 47 41
153 106 108 64 54
145 117 101 55 41
15 15 — — —
235+ = = = ea
213 a — — —
bones representing the manus, the paddle or foreflipper
exhibited the normal flattened condition of mysticetes. The
eighteen digital elements associated with this skeleton quite
probably do not belong to only one flipper since eleven
carpal bones were found. An estimate of the entire length
of the manus calculated on the basis of what seemed to be a
plausible arrangement of the recovered carpals, metacarpals
and phalanges suggests that it may not have exceeded 19%
inches (490 mm.) in length. The flipper itself would have
been approximately 45 inches (1145 mm.) long.
ScapuLta.—This broad fan-shaped scapula (fig. 21a)
exhibits no vestige of the existence of an acromion, although
A NEW
WHALEBONE WHALE
htt
\y a
LU NEN : A i
3”
ie,
(i
: mal
ls x
Ne
a
ny y
se (
ae
;
i =
1 Wwe ss
We sitter
FicuRE 22.—View of left humerus, USNM 11976, of Pelocetus calvertensis: a, external view;
b, internal view; c, view of distal end. Abbrs.: h., head; r.f., radial facet; r.t., radial
tuberosity; u.f.; ulnar facet.
the coracoid process is well developed. This condition can
hardly be regarded as an anomaly since the acromion is
lacking on both scapulae. Among Recent mysticetes, the
humpback whale (Megaptera) lacks both the acromion and
the coracoid processes. Unfortunately, the posterovertebral
angle is missing on both the right and left scapulae, but
nevertheless the maximum anteroposterior diameter when
complete must have exceeded 500 mm. The blade, which
is noticeably thickened on its basal half, becomes progres-
sively thinner toward the vertebral border.
The glenoid cavity (fig. 21b) is deeply concave and meas-
ures 110 mm. anteroposteriorly and 80 mm. exterointernally.
The spine of the scapula seems to be represented by the
prominent oblique dorsoventral ridge which fades into the
outer surface above the coracoid process and disappears near
but below the vertebral margin. The outer surface of the
scapula is marked by three, possibly four, ridges that radiate
upward from the depression above the glenoid border.
The fingerlike attenuated coracoid process projects outward
and slightly inward from the base of the scapula anteriorly
above the glenoid border, and measures about 65 mm. in
length, the free end being somewhat knoblike, and the inner
surface slightly flattened. The prescapular fossa is relatively
broad and flat, the maximum width being greater than
105 mm. The posterior margin of the scapula is concavely
curved in contrast to the convex curvature of the anterior
margin; the vertebral margin seems to have been somewhat
convex and presumably was characterized by a cartilaginous
condition similar to that of Recent mysticetes.
Measurements (in mm.) of the scapula of USNM 11976
are as follows:
Left Right
Maximum anteroposterior diameter of 420+ —
scapula, as preserved
Maximum vertical diameter, articular 360 =
head to vertebral margin
Length of coracoid, superior margin at 40+ =
base to distal end
Posterior face of articular head to distal 174 148+
end of coracoid
Maximum anteroposterior diameter of 115 108
articular head
Maximum transverse diameter of artic- 86 89
ular head
Humerus.—As in most mysticetes the humerus is rather
short, broad and robust. Both epiphyses are ankylosed to
38 UNITED STATES NATIONAL MUSEUM BULLETIN 247
the shaft. The humerus (fig. 22a) has a large, markedly
convex, smooth head which articulated freely in the con-
cave glenoid cavity of the scapula; its maximum diameter
is 115 mm. The head is placed obliquely on the shaft and
faces more or less outward and backward. The postero-
ventral border of the articular head is also traversed by a
shallow groove. Between the head and the large radial
tuberosity, the inner face of the proximal end of the humerus
is unusually rugose, including the large centrally placed
swelling or protuberance. On the humeri of Recent
mysticetes, the supraspinatus from the scapula and the
mastohumeralis are attached in this area; the rugose sur-
face of the large radial tuberosity serves as a similar proximal
area for attachment of the deltoideus. The rugose radial
tuberosity (fig. 22b) is rather broad, projecting externally.
The shaft is thickest below the head and is distinctly
flattened exterointernally toward the distal end. The
anterior or radial face (fig. 22a) of the shaft is markedly
rugose, most conspicuously so toward the tuberosity, pre-
sumably for the insertion of the deltoid muscle. The
hinder or ulnar face of the shaft is broader and more
rounded. The rugose area (fig. 22a) on the outer face of
the shaft between the head and the ulnar facet may possi-
bly indicate the position of the origin of the short head of
the triceps. On the lower or distal end (fig. 22c) of the
transversely flattened shaft the ulnar facet is slightly nar-
rower than the radial facet, more concave, saddle-shaped,
and extended upward on the posterior face of the shaft
distally. The radial facet is broad, flattened and set off
from the ulnar facet by an exterointernal ridgelike crest.
Measurements (in mm.) of the humerus of USNM 11976
are as follows:
Right Left
Maximum length of humerus 266.5 264
Maximum anteroposterior diameter of 153-5 151.5
proximal end
Maximum anteroposterior diameter of 114 112
head
Maximum exterointernal (transverse) 114 114.5
diameter of head
Least anteroposterior diameter of shaft 108. 5 108. 5
Least exterointernal (transverse) diame- 73-5 afi
ter of shaft
Maximum anteroposterior diameter of 127 125.5
distal end
Maximum exterointernal (transverse) 71.5 72
diameter of distal end
Maximum anteroposterior diameter of 71 69
radial facet
Maximum anteroposterior diameter of 70 73-5
ulnar facet (in a straight line)
PART 1
Rapius.—The right and left radius both have the proxi-
mal epiphysis ankylosed to the shaft, but the lower or distal
carpal epiphysis was not attached to either shaft. Among
the miscellaneous pieces recovered are two elongated rugose
and porous centers of ossification, the largest measuring
63 x 31 mm., which apparently represent incompletely
formed distal epiphyses. The radius (fig. 23a) is a rather
long, stout, slightly curved and transversely flattened bone,
measuring about 15% inches (398 mm.) in length.
The proximal facet which articulated with the radial
facet on the distal end of the humerus is shallowly concave,
its anteroposterior diameter being greater than the trans-
verse. This articular surface rolls over on the external and
internal faces of the proximal end of the shaft. The facet
on the posterior face of the proximal end (fig. 23b) for
articulation with the olecranon of the ulna is relatively
small, its transverse diameter being 42 mm. and the proxi-
modistal diameter 27 mm.
The outer and inner surfaces of the elongated shaft are
slightly convex. The shaft possibly has the posterior edge
sharper than the anterior. The distal extremity (fig. 23c)
of the shaft of both radii is rugose and deeply pitted which
indicates the presence of a cartilaginous cap or epiphysis.
Measurements (in mm.) of the radius of USNM 11976
are as follows:
Right Left
Maximum length 397 398
Maximum anteroposterior diameter of 84 =
proximal end
Maximum transverse diameter of proxi- 61 59-5
mal end
Least anteroposterior diameter near 78. 2 78
middle of shaft
Least transverse diameter near middle 40 43
of shaft
Maximum anteroposterior diameter of 88 89.5
distal end
Maximum transverse diameter of distal 48. 2 49
end
Utna.—Only the distal 220 mm. of the right ulna (fig. 24)
was recovered during the excavation of the skeleton. The
shaft was elongated, presumably of a length corresponding
to that of the radius, and noticeably widened at the distal
or carpal end. Viewed from the side the hinder profile is
more strongly curved than the anterior profile. The middle
portion of the shaft is oval in cross section. The shaft is also
rather imperceptibly bowed outward, the internal face being
rather flat and the external slightly convex. The distal or
carpal epiphysis was not ankylosed inasmuch as the distal
extremity of the shaft is very rugose and deeply pitted. One
small incomplete irregularly shaped porous bone (pl. 19,
A NEW WHALEBONE WHALE 39
FicurE 23.—Views of right radius, USNM 11976, of Pelocetus
calvertensis: a, internal view; b, posterior view; ¢, view of distal
end. Abbrs.: ant., anterior face; ext., external face; int., in-
ternal face; pt., posterior face.
fig. 10), similar in general appearance to the two heretofore
associated with the radii, presumably represents a portion
of the incompletely ossified distal epiphysis.
The measurements are as follows: minimum anteropos-
terior diameter of shaft near middle of its length, 50 mm.;
minimum transverse diameter of shaft at same level, 29 mm.;
maximum anteroposterior diameter of shaft at distal
end, 96.7 mm.; and transverse diameter of shaft at distal
end, 41 mm.
The right ulna (USNM 23059, pl. 16, fig. 1) of the referred
specimen is elongated, measuring 436 mm. in length, and
its relatively slender and transversely compressed shaft is
Ficure 24.—External outline of right ulna, USNM 11976, of
curved from end to end. From the upper margin of the
Pelocetus calvertensis.
755-999—65——_5
40 UNITED STATES NATIONAL MUSEUM BULLETIN 247
radial facet (radial margin) to the distal end the shaft
measures 365 mm. The distal or carpal end measures
76 mm. anteroposteriorly and 33 mm. transversely and is
roughened for cartilaginous attachment of the incompletely
ossified epiphysis which was found detached. The proximal
end is enlarged and thickened to form the backward pro-
jecting olecranon process. The curvature of the greater
sigmoid cavity forms about one quadrant of a circle, having
a diameter of approximately 100 mm. Near its upper end,
the articular surface of the greater sigmoid cavity does not
exceed 17 mm. in width, but measures at least 53 mm. near
the radial articular facet, whose dorsoventral diameter is
greatest internally. The posterior border of the olecranon
process is eroded.
Carpats.—The ten metapodials found during the ex-
cavation of the skeleton undoubtedly represent carpal
bones belonging to the manus of both forelimbs. There is
no certainty that not more than five centers of ossification
were present in each carpus. Four of these bones exhibit
to some degree the shape and appearance of carpals which
seemingly should be regarded as corresponding bones in
the right or left manus, even though allocation to either
the right or the left flipper cannot be made with certainty.
Although ossified, the orientation of the surfaces of all the
carpals remains uncertain. All of these carpals (fig. 25)
have fairly smooth dorsal and plantar surfaces, the other
faces being markedly irregular with interspersed nodosities
and pits. This roughening of the adjoining surfaces of these
bones indicates that the carpus was in a large part cartilag-
inous.
Tentative identifications are made for four carpals allo-
cated to the right manus (terminology of Kunze, 1912) by
comparison with the manus of flippers of skeletons of the
Recent Balaenoptera acutorostrata and Sibbaldus musculus in
FiGURE 25.—View of carpal bones, USNM 11976, of Pelocetus
calvertensis: a, radiale; b, pisiforme; c, intermedium; d, carpalia;
e, ulnare; f, carpalia.
PART 1
the United States National Museum. ‘The radiale in the
manus of both of these Recent mysticetes is the largest carpal
and is located in the proximal row anteriorly below the
distal end of the radius. The largest carpal of this Calvert
cetothere (fig. 25a; pl. 17, fig. 9) measures 70 mm. trans-
versely and 46 mm. in depth, and is thus assumed to be the
radiale.
The next largest carpal (fig. 25c; pl. 17, fig. 8) is 45 mm.
wide and 43 mm. deep; it is regarded as the intermedium.
Another carpal (fig. 25e; pl. 17, fig. 7) of somewhat similar
shape has a maximum diameter of 41 mm. and a depth of
40 mm., and is thought to be the ulnare. The dorsoplantar
measurements of three carpals (pl. 17, figs. 7, 8, 9) are
greater than those of two others presumed to have comprised
the distal row and thus seem to conform to the requirements
of the three in the proximal row. One somewhat elongated
carpal (fig. 25b; pl. 17, fig.1) with relatively small dorsal
and plantar smooth surfaces may represent the pisiforme.
FicurE 26.—Views of metacarpals, USNM 11976, of Pelocetus
calvertensis: a, right metacarpal III; 6, left metacarpal III; c,
right metacarpal IV.
The maximum transverse diameter of an irregularly
shaped fourth carpal (pl. 17, fig. 2) is 46 mm., and its
dorsoplantar diameter is 33 mm.; it is regarded as one of
the two carpals in the distal row as is another slightly small-
er bone (fig. 25f; pl. 17, fig. 3). The last mentioned carpal
is unquestionably a replica of one from the opposite manus.
Both differ from all other carpals in having two obliquely
directed flat faces which almost meet at an acute angle,
thus reducing the roughened faces to three.
METACcARPALS.—A number of bones belonging to the
manus were found associated with the skeleton of Cophocetus
oregonensis (Packard and Kellogg, 1934, pp. 54-58, fig. 21)
when it was excavated in the Miocene Astoria formation
at Newport, Ore. Of the eight bones found in close
proximity to the right ulna, three metacarpals (I, II, III)
were embedded in the matrix apparently in their natural
position and sequence. Neither the right nor the left
radius of C. oregonensis was found. As regards the left
manus, metacarpals IV and V were found lying side by side,
A NEW WHALEBONE WHALE
41
Plate 18
USNM 11976 — Metacarpals:
VSLASR CSD SET eN Yn YY SOC Ne SE fig.t Fig.7 Fig.5
Maximum length 99. 5 97-5 78 77 77-5 71 67 71.5
Minimum transverse diameter of shaft 34 35 37 39 34 31 18 36
Minimum thickness of shaft 23 25 20 20.5 24 22 17 15.5
Maximum transverse diameter of proximal end 55-5 57-5 46.5 43+ 47 42 30 41
Maximum transverse diameter of distal end 54 53 52.5 56 39 32 29 44.
and metacarpal III lay nearby. Metacarpal III is the
largest of the metacarpals and is readily recognizable.
Since the four remaining metacarpals are quite dissimilar
in appearance, there seems to be a reasonable basis for the
conclusion that the manus of C. oregonensis consisted of
five digits. Inasmuch as there exists a general resemblance
between the metacarpals of this Calvert cetothere and
those of Cophocetus, particularly metacarpal III, allocations
of individual bones of the digits have been made on the
assumption that five digits were present. It should be noted,
however, that so far as known the manus of Recent
balaenopterine whales is comprised of four digits (Kunze,
1912; Harmer, 1927, p. 61, fig. 30).
The digits are represented by sixteen essentially complete
bones and the extremities of two others. Six of these bones
(pl. 18, figs. 3 and 6, 1 and 4, as well as 2 and 9) thought to
be metacarpals seem to represent the same elements in
opposite flippers. The two largest bones (pl. 18, figs. 3
and 6) are less noticeably flattened in a dorsoplantar
direction than two other fairly large bones (pl. 18, figs. 2
and 9). Both ends of these four bones are roughened by
the presence of nodosities and pits, the proximal end being
more irregularly sculptured than the distal and by adherence
to cartilage. In the flipper of Recent mysticetes metacarpal
III is larger and longer than the others. Tentatively,
two of these bones (figs. 26a, 26b; pl. 18, figs. 3 and 6) are
allocated to metacarpal III. There may have been
limited contact between the proximal ends of metacarpals
II and III.
A somewhat shorter bone (pl. 18, fig. 5) not duplicated
among the bones recovered, is strongly flattened in a dorso-
plantar direction except proximally, and roughened at
both ends, the proximal end being truncated obliquely;
it is regarded as probably metacarpal I.
Two rather robust bones (pl. 18, figs. 1 and 4) whose
shafts are somewhat narrower, more cylindrical and less
flattened as well as relatively less widened transversely at
the distal end than the two larger metacarpals are identified
tentatively as metacarpal II.
The shafts of two bones (fig. 26c; pl. 18, figs. 2 and 9)
slightly shorter than metacarpal III are more noticeably
flattened and relatively wide transversely at the distal end;
they may represent metacarpal IV.
Two relatively slender bones (pl. 18, figs. 7 and 10)
possibly represent metacarpal V in opposite flippers. The
somewhat cylindrical shafts of these two metacarpals are
constricted near the middle of their length and expanded
at both roughened extremities.
Measurements (in mm.) of the metacarpals of USNM
11976 are tabulated above.
PHALANGES.—AIl but two (pl. 19, fig. 5; and pl. 18,
fig. 8) of these bones regarded as phalanges (fig. 27) are
noticeably flattened, more or less constricted near the middle
of their length and widened distally. The longest (pl. 19,
fig. 7) measures 85.5 mm. in length and the shortest (pl. 19,
fig. 2) 47 mm. Four of these bones have at least one end
roughened and truncated obliquely. In Recent mysticetes
the phalanges in each digit progressively diminish in
length from the proximal to the distal one. Presumably
not more than six or seven phalanges comprised the third
digit. If this assumption is correct at least one to three of
the shorter terminal phalanges are not here represented for
any digit. Two very slender phalanges (pl. 18, fig. 8; and
pl. 19, fig. 5), much wider proximally than distally, and
measuring 46 and 51 mm. in length respectively are re-
garded as belonging to the first digit in opposite flippers.
Measurements (in mm.) of the phalanges of USNM
11976 are tabulated below.
USNM 11976 — Phalanges: Rigi 19 plates
Fig.7 Fig.6 Fig.r Fig.3 Fig.2 Fig.g Fig.5 Fg. 8
Maximum length 85.5 68. 5 68. 5 54 47 47 51 46
Minimum transverse diameter of shaft 32.5 29 28 24 aI 22.5 9-5 9-5
Minimum thickness of shaft 17 16 16 II 10 11.5 9 9
Maximum transverse diameter of proximal end 48 42 36 33 30 33 19.5 20
Maximum transverse diameter of distal end 46. 5 43 44. 5 28.5 31.5 32.5 10.5 II
492 UNITED STATES NATIONAL MUSEUM BULLETIN 247
a b C d
FicuRE 27.—Views of phalanges, USNM 11976, of Pelocetus
calvertensis: a and 6, small phalanges; c, medium size phalange;
d, large phalange.
Sternum
One or more of four bones (pl. 20) not otherwise identi-
fied with some part of the skeleton may possibly represent
the sternum. These bones do not, however, agree with
the sternum of living mysticetes, which in some species
consists of a broad flattened presternum extended back-
ward into a ziphoid process. In these Recent whalebone
whales this bone varies in shape from heart-shaped, longi-
tudinally oval to trilobate. True (1904, pp. 140-141)
has figured the extreme variability of the sternum of
Balaenoptera physalus. No mesosternal elements are retained
and hence no ribs other than the first pair are attached to
the sternum. Except for the heart-shaped sternum of
the Miocene Cetotherium klinderi figured by Brandt (1873,
pl. 5, figs. 13A, 13B), the cetothere sternum seems to have
escaped the notice of cetologists. The largest of these
Calvert bones (pl. 20, fig. 2) measures 112 x 76 mm.;
it is somewhat heart-shaped and is produced medially
into a rather large, blunt tuberosity whose apex is elevated
50 mm. above the opposite concave surface. Although
ossified, all the rather thick free edges are irregularly
sculptured, presumably for adherence of cartilage. The
ventral and dorsal faces of this bone are pitted and slightly
roughened. ‘The longest free edge of the thickest of these
four bones (pl. 20, fig. 1) is deeply pitted, no doubt for
attachment of cartilage. Both of the two smallest bones
(pl. 20, figs. 3, 4) possess one deeply sculptured edge and
one rounded edge; the other edges are incomplete. No
satisfactory interpretation of the relative positions of these
bones, if all do pertain to the sternum, is readily apparent.
Ribs
All of the ribs found associated with this skeleton are
incomplete and all lack varying lengths of their distal
extremities. The proximal portions, however, of eleven
of the twelve ribs are sufficiently complete to permit
accurate description. The first rib has but one terminal
facet which articulates with the end of the transverse
process (diapophysis) of the first dorsal vertebra. Only
the first pair of ribs articulates or is connected with the
sternum in all living mysticetes, and this condition may
have prevailed on this fossil whale skeleton. The second
PART 1
to ninth ribs, inclusive, possess two articulating surfaces,
one (the tuberculum) having a ligamentous attachment to
the end of the transverse process and the other (the
capitulum) to the posterodorsal facet on the lateral surface
of the centrum. The tenth, eleventh and twelfth ribs
have a single, horizontally elongated head. The second
rib has a noticeably elongated and anteroposteriorly flat-
tened neck; the shaft is abruptly turned downward below
the rather small tubercular facet. The vertebral end of
the shaft of the third rib is likewise anteroposteriorly
flattened, but the neck is shorter and stouter. On the
fourth, fifth, sixth and seventh ribs, the shafts are noticeably
thicker, the necks rather short, and the distance from the
capitular end to the angle (the point where the shaft is
turned downward) is progressively increased. The neck
of the eighth rib is slightly longer than the preceding, the
shaft is more slender and the angle is much less noticeably
developed. No neck is retained on the tenth rib and
the elongated head is dorsoventrally compressed; the
distal third of the shaft is thin, compressed and attenuated.
On the eleventh rib the vertebral end of the shaft is some-
what circular in cross section, but the rest of the shaft
becomes progressively more flattened toward the distal
end, which is distinctly twisted backward. Although the
twelfth rib lacks the distal portion, its dimensions indicate
amuchshorter and moreslender shaft, which is dorsoventrally
compressed proximally (for a length of 125-+- mm.) and
flattened anteroposteriorly on the remainder of the shaft.
First Rib: Of the twelve pairs of ribs the first obviously was
the shortest. This rib (pl. 21, fig. 1) has a stout heavy shaft
which is rather regularly curved from the capitular end to
the broken-off extremity; the capitular portion of the shaft
is malformed by exostosis. The characteristics of the sternal
end are unknown. The thoracic face of the shaft is slightly
flattened in contrast to the convexity of the other faces.
Second Rib: The vertebral end of the shaft is markedly
flattened in an anteroposterior direction and widened in an
externointernal direction; the broken distal end of the shaft
is ovoidal in cross section (35x 30 mm.). Both tubercular
and capitular facets are small, that of the latter is slightly
larger than the former; the compressed neck (pl. 21, fig. 2)
is elongated (distance between outer margin of the capitu-
lum and inner margin of tubercular facet, 100 mm.) and
is bent slightly backward.
Third Rib: Only the vertebral end of the shaft of this rib
(pl. 21, fig. 3) is preserved. It is similarly compressed, but
noticeably widened, the neck is markedly shortened (dis-
tance between outer margin of capitulum and inner margin
of tubercular facet, 44 mm.) and strongly bent upward.
The capitular facet is large, and knoblike; the tubercular
facet is elongated and its thoracic border overhangs that
face of the shaft.
A NEW WHALEBONE WHALE 43
Fourth Rib: The shaft (pl. 21, fig. 4) is thick, stout,
flattened on the thoracic face proximally, but otherwise
convex, and is turned abruptly downward below the angle.
The concave ovoidal tubercular facet is larger than the up-
turned knoblike capitulum and overhangs the external face
of the shaft. The neck is rather short (distance between
outer margin of capitulum and inner margin of tubercular
facet, 35 mm.); the dorsoventral diameter of the neck is
greater than its anteroposterior diameter.
Fifth Rib: The shaft (pl. 21, fig. 5) is thick, stout, almost
subquadrangular in cross section near the angle, below
which it is turned abruptly downward. The concave
tubercular facet is almost saddleshaped and much larger
than the knoblike capitulum; it overhangs both faces of the
shaft. The neck is short (distance between outer margin
of capitulum and inner margin of tubercular facet, 37 mm.)
and its depth is greater than its breadth. The distance
between the articular face of the capitulum and the angle
of the shaft is 190 mm.
Sixth Rib: The shaft (pl. 21, fig. 6) is almost as stout as
that of the fifth rib and the distance between the articular
face of the capitulum and the angle of the shaft is 210 mm.
On both the thoracic and outer surfaces the shaft is pro-
gressively compressed toward the distally widened extremity.
The concave tubercular facet is noticeably wider than the
upturned knoblike capitulum and overhangs both faces of
the shaft; the thick neck is short (distance between outer
margin of capitulum and inner margin of tubercular
facet, 33 mm.) and its depth is about equal to its breadth.
Seventh Rib: The shaft (pl. 21, fig. 7) is distinctly more
slender than that of the sixth rib and the distance between
the articular face of the capitulum and the angle of the
shaft is 235 mm. Proximally the shaft is subquadrangular
in cross section below which this contour is modified by
strong compression in a thoracic-external direction as well
as a more obvious flattening of the thoracic face distally.
The somewhat flattened tubercular facet is smaller than
the knoblike capitulum. The stout neck is short (distance
between outer margin of capitulum and inner margin of
tubercular facet, 35 mm.).
Eighth Rib: The shaft (pl. 21, fig. 8) is slender, but
compressed distally; the angle of the shaft is even farther
removed (265 mm.) from the articular face of the capitulum
than on the seventh rib. On this rib, the tubercular facet
is largely destroyed, but was separated from the large
knoblike capitulum by at least 50 mm.
Ninth Rib: This rib has not been recognized among the
rib fragments associated with this skeleton.
Tenth Rib: The vertebral end of this slender elongated
rib (p. 21, fig. 9) is compressed in a thoracic-external
direction, but has no visible neck. The narrow articular
head is horizontally widened and is rather rugose for its
ligamentous attachment to the end of the transverse process.
The shaft is thickest near the end of the proximal third of
its length, below which a rather sharp crest is developed on
the posterior face; its distal end is flattened, attenuated
and incurved. This rib measures along the outside curve,
930 mm., but the distal end is not complete.
Eleventh Rib: The shaft (pl. 21, fig. 10) is narrowest,
almost circular in cross section, proximally, but is strongly
compressed distally as well as bent backward near the
extremity. Both edges of the shaft on this lower section
are rather sharp or crestlike.
Twelfth Rib: This rib (pl. 21, fig. 11) was obviously
shorter than the preceding rib. Its narrowed and horizon-
tally elongated articular head (fig. 28) is located on the
obliquely truncated vertebral end of the shaft, which is
strongly compressed in a dorsoventral direction for about
125 mm. below this end. The shaft then twists so that
the remaining distal portion is compressed in an antero-
posterior direction, the posterior edge being rather sharp.
The end-to-end curvature is relatively slight.
Ficure 28.—Lateral view of twelfth rib, USNM 11976, of Peélocetus calvertensis.
44 UNITED STATES NATIONAL MUSEUM BULLETIN 247
BIBLIOGRAPHY
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PART 1
A NEW WHALEBONE WHALE
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2. The Miocene Calvert Sperm Whale
Orycterocetus
(amen SORT OF REMODELING of the skull led to the
separation of the physeteroid stock from other odon-
tocetes which, with the exception of the ziphioids, seem to
have followed a more conventional line of development in
cranial architecture. As early as the lower Miocene, sperm
whales were differentiated by these cranial modifications
from the main odontocete stocks. On the skulls of two
lower Miocene genera (Diaphorocetus and Idiorophus), the
adipose cushion, or reservoir for spermaceti, had spread
backward behind the nasal passages and the consequential
adjustment of involved cranial bones formed a supracranial
basin. The ‘‘dishing-in” of the roof of the braincase is
attributable in part, at least, to the pressure of this develop-
ing spermaceti reservoir. The accompanying alterations
of the relative proportions and relations of the dorsal cranial
bones included the depression of the frontal bones along
the median longitudinal line, the posterior enlargement or
widening of the upturned right premaxillary, the crestlike
elevation of the maxillaries laterally, the loss or marked
reduction of one of the nasal bones and the flattening of the
other against the frontal behind the greatly enlarged left
nasal passage, and the marked widening of the rostrum
proximally. Some genera of extinct physeteroids retain
a functional dentition in the upper jaws to the close of their
known geological history. Other genera exhibit a tendency
for the teeth to become loosely implanted in large alveoli,
while the intervening septa diminish in thickness and ul-
timately disappear, leaving an open alveolar gutter in the
maxillary (Aulophyseter). Teeth were lodged in distinct
alveoli in each maxillary of this Calvert Miocene Orycterocetus.
Owen seems to have been the first to recognize the phy-
seteroid affinities of a Tertiary fossil tooth, and consequently
Balaenodon (Owen, 1846, p. 536, figs. 226-229) became the
first generic name to be applied to a fossil sperm whale.
The type of Balaenodon physaloides Owen comprises a portion
of the root of a tooth from the Red Crag of Felixstowe,
Suffolk, England. Abel (1905, p. 52) concluded that with-
out doubt this tooth belonged to the physeteroid Scaldicetus
carettt, but that the basis for validation of the scientific name
was insufficient. The type tooth, however, is considerably
larger and structurally different from the teeth of
Orycterocetus.
The next oldest available name for a fossil sperm whale is
Hoplocetus Gervais (1849, p. 161, pl. 20, figs. 10-11) based
on two teeth found in the middle Miocene shell marl (faluns)
in the vicinity of Romans, Department Dréme, France.
The two type teeth of Hoplocetus crassidens (type species) are
characterized by an enlarged or swollen root set off from a
proportionately small crown by a necklike constriction.
Abel (1905, p. 53) rejects the validity of the stated generic
characters of Hoplocetus, but nevertheless places it in the
synonymy of Scaldicetus. The pulp cavity is closed on one
of these teeth and reduced to a vestige on the other.
The teeth of Scaldicetus caretti aside from their larger di-
mensions are characterized by having the enamel on the
crown very coarse and rugose, the ridges anastomosing but
generally running toward apex of crown with numerous
connecting or intersecting striae; no perceptible constriction
of the root at base of crown.
Inasmuch as the above-mentioned extinct physeteroids
cannot conceivably have any bearing on the generic alloca-
tion of the Calvert Miocene sperm whale, no further con-
sideration is given to their status.
ORYCTEROCETUS Leidy
Orycterocetus Leidy, Proc. Acad. Nat. Sci. Philadelphia, vol. 6
(1852-53), p. 378, August 1853.
Type Species: Orycterocetus quadratidens Leidy.
Diagnosis: Twenty teeth in each upper jaw (17 of which
were lodged in alveoli in maxillary and 3 present on pre-
maxillary). Dentine core of slender curved teeth often
with open funnellike pulp cavity; fine annular lines of
47
48 UNITED STATES NATIONAL
growth and longitudinal fluting characterize the dentine
core of larger teeth; outer layer of cementum may completely
cover the dentine on undamaged teeth; conical tip or crown
of teeth occasionally black and polished, but lacks enamel;
no perceptible distinction between crown and root or
visible constriction to form neck below crown. Vertex of
cranium eliminated by development of large supracranial
basin for reception of reservoir for spermaceti. Supra-
cranial basin bounded laterally on right side by elevated
border of right maxillary; on left side by left premaxillary
and elevated crest of underlying left maxillary; and pos-
teriorly by hinder borders of both maxillaries which over-
ride medially the posterior ends of the frontals and abut
against the dorsal crest of the supraoccipital. Right nasal
bone either lost or greatly reduced; the left nasal bone
flattened against the frontal behind greatly enlarged left
nasal passage and partially concealed by squamous overlap
of markedly expanded posterior portion of right pre-
maxillary.
ORYCTEROCETUS QUADRATIDENS Leidy
Orycterocetus quadratidens Leidy, Proc. Acad. Nat. Sci. Philadelphia,
vol. 6 (1852-53), p. 378, August 1853.
Type Specimen: Two teeth, together with small frag-
ments of a jaw (ANSP 9065-69), presented by Prof.
Francis Simmons Holmes.
Horizon and Locality: Miocene formation, Virginia.
Leidy (1853, p. 378; 1869, pp. 436-437, pl. 30, figs.
16-17) has characterized the two type teeth as being long
and conical, one being nearly straight, the other strongly
curved. Both teeth in transverse section are rather ovoidal
near the tip, but more quadrate near the base. The annular
lines of growth are strongly marked and _ longitudinal
fluting is present on the dentine. A thin patch of cementum
is present on one side at the base of one tooth, but no
enamel. No perceptible distinction between crown and
root exists. A funnellike pulp cavity is open at the base of
the root. The largest tooth measures about 127 mm. (5
inches) in length and the diameters at the base 21.16 and
23.27 mm.
No characters of generic importance can be defined to
distinguish these teeth from Orycterocetus crocodilinus. The
quadrate transverse shape of the basal portion of the root
of this physeteroid may possibly indicate a specific differ-
ence unless it can be shown that teeth with identical
features are present in the Calvert formation. The only
information at present available is that the type teeth
came from the ‘Miocene formation” of Virginia, which
as currently recognized would include the Calvert, Chop-
tank, St. Marys and Yorktown formations. It would seem
advisable to defer a decision as to the possible identity of
this species with O. crocodilinus until teeth with identical
MUSEUM BULLETIN 247 PART 2
characteristics are found in the Calvert formation, or more
precise information regarding the source of the type teeth
of Orycterocetus quadratidens is located in contemporary
records.
ORYCTEROCETUS CROCODILINUS Cope
Orycterocetus crocodilinus Cope, Proc. Acad. Nat. Sci. Philadelphia,
vol. 19 (1867), p. 144, Mar. 10, 1868.
Type Specimen: One tooth. (ANSP 9126), collector,
James T. Thomas, October 1867.
Horizon and Locality: Charles County, Md., not far
from the Patuxent River in “Yorktown” beds [Near the
Patuxent River, not far from the home of James T. Thomas,
about one mile east of site marked Patuxent (U.S.G.S.
sheet Brandywine, Md.), two miles east of Hughesville,
Charles County, Md.]. Calvert formation, upper Miocene.
Cope describes the single tooth on which this species
is based as having the form of an elongate curved cone,
with flattened sides, the posterior face being convex and
broad, and the anterior face narrower; no enamel is present
on the apical portion. The tip of the crown is worn,
which Cope regards as attesting maturity. Irregular
transverse annular growth lines and more or less parallel
longitudinal grooves are present on the dentine core.
The large pulp cavity of this tooth is open at the base and
extends two-thirds of the length of the tooth. The measure-
ments given by Cope for this tooth are as follows: length,
61.38 mm.; diameter at base, 17.46 mm.; diameter at
middle, 12.7 mm. The type tooth is figured by Case
(1904, pl. 18, fig. 7).
Referred Specimens: Eighteen, as follows: (1) USNM
1158: one tooth, coll. Frank Burns, 1892; Jones Wharf, St.
Marys Co., Md., Choptank formation, middle Miocene.
(2) USNM 8575: one tooth, coll., Mark M. Shoemaker,
1916; Chesapeake Beach, Calvert Co., Md., Calvert
formation, middle Miocene. (3) USNM 8576: one tooth,
coll. Mark M. Shoemaker, 1916; Chesapeake Beach,
Calvert Co., Md., Calvert formation, middle Miocene. (4)
USNM 11234: right periotic, coll. A. Wetmore, May 24,
1925; Chesapeake Beach, Calvert Co., Md. Calvert
formation, middle Miocene. (5) USNM 13778: one tooth,
coll. Mrs. J. Homer Smith; Plum Point, Calvert Co., Md.
Calvert formation, middle Miocene. (6) USNM 14729:
skull lacking distal end of rostrum, supraorbital processes
of frontals, occipital condyles, palatines and pterygoids,
coll. R. Lee Collins and W. Gardiner Lynn, July 1, 1935;
in fallen block of sandy clay, presumably from Zone 11,
¥% mile south of Randle Cliff Beach, Calvert Co., Md.
Calvert formation, middle Miocene. (7) USNM 14730;
skull lacking distal end of rostrum, zygomatic processes,
palatines and pterygoids, coll. William F. Foshag, July 25,
1936; base of Zone 12, about 18 inches above high tide
THE SPERM WHALE ORYCTEROCETUS 49
level, % ) mile south of mouth of Parker Creek, [in third
cliff south of mouth of Parker Creek, about 820 yards],
Calvert Co., Md., Calvert formation, middle Miocene.
(8) USNM 22926: skull essentially complete, except for
missing distal end of rostrum and postorbital projection
of right supraorbital process, left periotic, 16 teeth,
posterior end of left mandible, and rib fragments, coll.
Wallace L. Ashby, Jr., Feb. 24, 1959; about 100 yards
south of north end of first cliff south of mouth of Parker
Creek, in Zone 13 (6 feet below zone 14), Calvert Co., Md.,
Calvert formation, middle Miocene. (9) USNM 22930:
incomplete skull of young sperm whale, comprising right
side of top of braincase, left supraorbital process detached,
basicranium with both exoccipitals and zygomatic processes,
and short section of frontal-supraoccipital crest, coll.
W. Gardiner Lynn, Apr. 1935; %) mile south of mouth of
Parker Creek, in Zone 12, about 3 feet above beach level.
Calvert formation, middle Miocene. (10) USNM 22931:
rostrum complete anterior to maxillary incisure; right
zygomatic process incomplete; portion of basioccipital and
miscellaneous bone fragments, coll. W. Gardiner Lynn and
R. Lee Collins, August 1934; about 1.2 miles south of
Chesapeake Beach, near top of Zone 9, about 25 or 30 feet
above beach level, Calvert Co., Md., Calvert formation,
middle Miocene. (11) USNM 22932: one tooth, collector
and date not recorded; \ mile from mouth of Parker Creek,
Calvert Co., Md., Calvert formation, middle Miocene.
(12) USNM 22933: four isolated teeth, coll. Remington
Kellogg, Sept. 27, 1925; in Zone 10 (shell band) 2 feet
above water level at high tide, % kilometer south of Plum
Point wharf, Calvert Co., Md., Calvert formation, middle
Miocene. (13) USNM 22934: one tooth, coll. R. Lee
Collins, Sept. 15, 1936; found on beach, % mile south of
Plum Point wharf, Calvert Co., Md., Calvert formation,
middle Miocene. (14) USNM 22935: nine isolated
teeth, collector and date not recorded; probably from beach,
Calvert Co., Md., Calvert formation, middle Miocene.
(15) USNM 22952: left periotic, coll. R. Lee Collins and
W. Gardiner Lynn, 1934-1935; South Chesapeake Beach,
Calvert Co., Md., Calvert formation, middle Miocene.
(16) USNM 22953: Right periotic, right tympanic bulla,
and laminated spongy osseous mass associated with extrem-
ity of posterior process of bulla, coll. R. Lee Collins,
May 15, 1937; in fallen block of sandy clay from Zone 14,
about %> mile south of Randle Cliff beach, Calvert Co.,
Md., Calvert formation, middle Miocene. (17) USNM
22967: 390 mm. long posterior rostral fragment of left
maxillary, coll. Wallace L. Ashby, Jr., March 1954;
Zone 12, 36 yards south of small cove in cliff south of
Parker Creek, Calvert Co., Md., Calvert formation,
middle Miocene. (18) USNM 10860: right periotic and
detached accessory ossicle, coll. F. W. True (original no.
844), date not recorded; Calvert Cliffs, Calvert Co., Md.,
Calvert formation, middle Miocene.
Skull
Bilateral asymmetry of the skull (fig. 29) is accentuated
in all fossil and Recent physeteroids. The distortion result-
ing from this alteration of the usual relationships of the
bones comprising the roof of the cranium is not restricted
to the region of the nasal passages, but involves all the bones
that contribute to the formation of the supracranial basin.
A 390 mm. long posterior rostral fragment of the left
maxillary (USNM 22957) tends to confirm the assumption
that the four skulls hereinafter described may represent
growth stages of this Calvert physeteroid. On the basis of
comparative measurements the skull, of which this maxillary
fragment was a relic, is estimated to have measured 950 mm.
in length, as contrasted to 830 + mm. for the largest of the
four skulls.
It should also be noted that among living cetaceans, the
male sperm whale attains a much greater size than the
female. If this disparity between the dimensions of males
and females also characterized the sexes of these Miocene
physeteroids, the possibility also exists that this large rostral
fragment may have been derived from a male. The pres-
ence of the skull of a quite young individual (USNM
22930) suggests that these Calvert Miocene waters may
have been a calving area.
DorsaL view.—From a dorsal view (pl. 22) the skull of
this Miocene sperm whale differs most obviously in some
minor details from that of a young Recent Physeter catodon
(Kellogg, 1925, pl. 6), the right premaxillary bone being
markedly widened behind the nasal passages, overriding
the flattened nasal bone, and almost coming in contact
with the posterior end of the left premaxillary. These pre-
maxillaries comprise the dorsal surface of the middle longi-
tudinal portion of the rostrum and the rather deep supra-
cranial basin. This posterior widening of the right pre-
maxillary seems to have its closest counterpart in the
lower Miocene Diaphorocetus poucheti (Lydekker, 1894,
pl. 3). Asin the Patagonian sperm whale a small foramen
(the orifice looking upward and connecting ventrally with
the infraorbital system) pierces the maxillary on both the
inner and the outer faces of the lateral crest of the supra-
cranial basin, the inner one at the level of the center of the
orbit and the outer one usually behind the supraorbital
process. The larger maxillary foramen opens into the
slitlike incisure in the maxillary between the antorbital
notch and the supracranial basin. The posterior end of the
maxillary overrides the underlying frontal above the tem-
poral fossa and contributes the lateral border of the supra-
cranial basin.
50
UNITED STATES NATIONAL MUSEUM BULLETIN 247 AR
FicuRE 29.—Dorsal view of skull, USNM 22926, of Orpcterocetus
crocodilinus, with anterior end of rostrum restored. Abbrs.:
ant.n., antorbital maxillary notch; ap.max., maxillary
apophysis; C., occipital condyle; f.max., maxillary incisure;
f.pmx., premaxillary foramen; Ex.oc., exoccipital; Fr.,
frontal; j.n., jugular incisure; Max., maxillary; max.cr.,
maxillary crest; Na., nasal; Pmx., premaxillary; pr.s., pre-
sphenoid; S.oc., supraoccipital; s.or.pr., supraorbital process
of frontal; Vo., vomer; zyg., zygomatic process of squamosal.
THE SPERM WHALE ORYCTEROCETUS 51
The opposite premaxillaries of all known fossil and recent
physeteroids are dissimilar in form. The upper surface of
the right premaxillary in front of the premaxillary foramen
is concave for a distance of about 150 mm. on two skulls
(USNM 14729 and 14730) and convex on the other skull
(USNM 22926). As a result of telescoping, the right pre-
maxillary is extended backward on the upper surface of
the cranium to the posterior borders of the maxillaries.
Posterior to the nasal passages the right premaxillary ex-
pands into a broad, thin plate which is applied to the upper
surface of the frontal, overlapping the maxillary externally
and posteriorly. A large foramen pierces the right pre-
maxillary anterior to the level of the maxillary incisure.
On its internal border behind the nasal passages the right
premaxillary overrides and partially conceals the flattened
nasal bone except for a maximum 53 mm. wide exposure
of its external border. The left premaxillary has been
pushed outward by the enlargement of the left nasal passage
and terminates 115 to 130 mm. behind the level of the
posterior wall of this passage. No foramen is present on
the left premaxillary anterior to the nasal passages. The
inner borders of the premaxillaries are closely approxi-
mated in front of the presphenoid but do not completely
roof over the mesorostral gutter on any one of the four fossil
skulls. Anterior to the widest basal portion of the rostrum
(fig. 30), the upper surfaces of the premaxillaries become
progressively more convex and on USNM 22931 comprise
one half or more of the vertical diameter on the distal 280
mm. of the lateral surface of the rostrum. Anterior to the
widest basal portion of the rostrum the downward slope
of the upper surface of the premaxillaries becomes more
pronounced and is accentuated near the extremity. The
premaxillaries (pl. 28 top) by themselves comprise the
distal 75 mm. of the rostrum (USNM 22931) of the best
preserved specimen. For more than half the length of the
rostrum in front of the mesethmoid, the floor of the meso-
rosiral gutter is formed by the anterior extension of the
vomer and the sides and the roof by the premaxillaries;
the distal 130 to 150 mm. is contributed entirely by the
premaxillaries. The premaxillaries of this Calvert sperm
whale skull resemble more closely those of Diaphorocetus
poucheti than comparable cranial portions of any other
described form, with the possible exception of the incom-
pletely preserved skull (Abel, 1905, fig. 7) of Thalassocetus
antwerpiensis. ‘The side to side constriction of the anterior
half or more of the rostrum resembles rather closely that of
D. poucheit.
On one skull (USNM 14730) the distance from the poste-
rior margin of the left nasal passage to the posterior face of
the left occipital condyle is about half the distance from
the anterior margin of the same passage to a point where
the corresponding maxillary is no longer visible from a dorsal
view.
The maxillaries are the largest elements in the rostrum
and contribute the major portion of the palatal surface.
The antorbital notches are deep and narrow. The rostrum
is widest at the level of the anterior margin of the antorbital
notches. As viewed from the dorsal side, the maxillaries
are visible for a relatively greater distance toward the ex-
tremity of the rostrum on USNM 22926 than on USNM
22931. Unfortunately the extremity of the rostrum (pl. 22)
of USNM 22926 is not preserved, and the left maxillary
was broken off 410 mm. anterior to the level of the antor-
bital notches and was still visible some 180 mm. in front
of the level of the anterior end of the vomer exposed on the
palatal surface of the rostrum. On the better preserved
rostrum (USNM 22931) each maxillary disappears from
the' dorsal view approximately 30 mm. in front of the level
FicurE 30.—Dorsal view of rostrum, USNM 22931, of Oryctero-
cetus crocodilinus. Abbrs.: Max., maxillary; Pmx., premaxillary;
Vo., vomer.
52 UNITED STATES NATIONAL MUSEUM BULLETIN 247
of the anterior end of the vomer. As will be observed from
a palatal view (pl. 28 bottom) the premaxillaries comprise
the distal 75 mm. of the rostrum (USNM 22931). It is
obvious that little or no importance should be attributed to
the dorsal exposure of the maxillaries as this bone is visible
for a distance of 300 mm. anterior to the level of the antor-
bital notches on another skull (pl. 25, USNM 14730) and
disappears from a dorsal view on USNM 14729 at least
200 mm. behind the broken extremity of the rostrum and
290 mm. anterior to the level of the antorbital notches.
Posterior to the antorbital notch, each maxillary is dorso-
ventrally thickened and contributes to the sloping outer
wall of the supracranial basin. This posterior portion of
the maxillary overrides the frontal, but leaves exposed a
very narrow strip of the outer orbital portion of the supra-
orbital process. When the skull is viewed from above, the
slender apophysis of the maxillary conceals the lachrymal
(which is lost on all three crania) from a dorsal view. The
maxillary incisure is quite variable in size and shape on the
three skulls. A longitudinal depression is present on the
dorsal surface of the maxillary in front of the maxillary
incisure on one skull (USNM 22926) but is either absent
or much less developed on the other two skulls. The
posterior maxillary foramina although continuous intern-
nally with the maxillary incisure open into short posteriorly
directed furrows.
The facial depression or supracranial basin (pl. 25), in
which the spermaceti organ rests, occupies a large area on
the dorsal surface of the skull. This supracranial basin is
bounded posteriorly by the upturned and curved crestlike
hinder borders of the two maxillaries which in turn are
thrust backward against the upper border of the supra-
occipital, The outer wall of the supracranial basinis
contributed on the right side by the maxillary and on the
left side by the premaxillary which overrides the correspond-
ing portion of the maxillary. This basin is terminated an-
teriorly on the proximal portion of the rostrum.
Above the temporal fossa (pl. 27 top) the outer margin
of the maxillary (USNM 14730), follows the underlying
border of the frontal and does not project laterally beyond
the latter. The postnarial portion of the right maxillary
is separated by an interval of about 16 mm. from the left
maxillary at the middle of the supraoccipital crest (USNM
22926). The depression of the supracranial basin has not
modified the maxillaries to the same extent as the pre-
maxillaries were altered.
The left respiratory passage (pl. 25) is bounded by the
ethmoid on the inner side, by the left premaxillary in front
and externally, and by the nasal and left premaxillary
behind. Ventrally the vomer curves around the inside
and back of each passage while the pterygoid and its hamu-
lar process (USNM 22926) contributes the remainder of
the ventral border.
PART 2
The laterally compressed presphenoid contributes the
pluglike projection at the posterior end of the mesorostral
gutter. Along with the enlargement of the left nasal
passage, the presphenoid has been shoved leftward; laterally
it slopes obliquely downward from left to right and its
main axis forms an angle with the longitudinal axis of the
rostrum. The mesethmoid is rather intimately coalesced
with the presphenoid and apparently this bone contributes
a portion of the posterior wall of the left nasal passage
(USNM 14730). Each lateral wing of the presphenoid,
the orbitosphenoid, is seemingly coalesced with the cranial
portion of the corresponding supraorbital process of the
frontal as in a young Physeter skull (Kellogg, 1925, pl. 6).
The open furrow for the optic nerve on the ventral face
of the supraorbital process of the frontal terminates in-
ternally. This portion of the frontal abuts posteriorly
against the alisphenoid. No orifices for the olfactory
nerves are present and hence the sense of smell has been
lost. If ectethmoids are present they are coalesced with
the mesethmoid which apparently contributes the most
dorsal portion of the partition between the nasal passages.
Although a careful search was made on these three
skulls for small foramina in the posterior walls of the nasal
passages which would give passage for the ophthalmic
division of the trigeminal nerve none were noted.
On these Calvert skulls the upwardly curved platelike
portions of the frontals meet on the midline, roof over the
braincase, and abut against the dorsal border of the supra-
occipital. On the young skull (USNM 22930) and that of
the oldest individual (USNM 22926) the posterior edge
of the frontal underlying the right maxillary is exposed
in front of the dorsal crestlike edge of the supraoccipital.
The zygomatic processes are more elongated and more
outwardly bowed (pl. 23) than in Diaphorocetus poucheti
(Lydekker, 1894, pl. 3). Each platelike exoccipital which
abuts against the corresponding squamosal curves forward,
but projects backward beyond the level of the supra-
occipital shield when viewed from above.
POSTERIOR VIEW.—Since the occipital surfaces of two of
these skulls are incomplete in one respect or another, the
description of this surface (pl. 24 top) will be based on the
largest skull (USNM 22926). The supraoccipital shield
above the condyles slopes forward and is concavely curved
from side to side; its relatively thin projecting flangelike
external border contributes the posterior boundary of
the temporal fossa. The exoccipitals (pl. 27 bottom) are
relatively large, anteroposteriorly compressed bones, some-
what curved from side to side and partially conceal from a
posterior view the corresponding zygomatic process.
Anteriorly each exoccipital is suturally united with the
squamosal, internally fused with the basioccipital, and
dorsally merged imperceptibly into the supraoccipital.
The deep jugular incisure (pl. 24 top) separates the internal
THE SPERM WHALE ORYCTEROCETUS 53
margin of the exoccipital from the hinder end of the
elongated falcate process of the basioccipital. Ventral to
the occipital condyles and internal to the exoccipitals
are the falcate processes of the basioccipital. The posterior
ends of the hamular processes of the pterygoids are visible
in front of and between the falcate processes. “The foramen
magnum is relatively large. The protuberant occipital
condyles exhibit a greater transverse width dorsally than
ventrally, and are convex from side to side. ‘The internal
borders of the condyles are concave; they are more closely
approximated ventrally than dorsally.
LaTERAL view.—As seen from a lateral view, all three
skulls are crushed to a varying degree. The largest skull
(USNM 22926), although depressed somewhat, is the most
complete. From about the middle of the length of the
rostrum backward (pl. 24 bottom) the outer margin of the
maxillary rises gradually to the antorbital notch. Begin-
ning at the level of the fourteenth alveolus, counting back-
ward from the anterior end of the maxillary tooth row, the
oblique upward slope of the external face of the maxillary
becomes accentuated so that it is nearly vertical in front
of the ninth alveolus. Between the ninth alveolus and the
antorbital notch the maxillary becomes progressively more
compressed dorsoventrally. ‘The apophysis of the maxillary
is relatively large as compared to the supraorbital process
of the frontal. The maxillary overrides the supraorbital
process as well as the cranial portion of the frontal and
ascends upward in a strong curve to the dorsal crest of the
posterior face of the skull. The postorbital projection of
the supraorbital process is more elongated than the post-
orbital portion and is turned downward and presumably
came in contact with the anterior end of the zygomatic
process.
On the type skull of Thalassocetus antwerpiensis (Abel, 1905,
fig. 8) the slope of the outer border of the frontal and over-
lying maxillary above and behind the orbit is similar to
that exhibited by the skull of Orycterocetus crocodilinus (USNM
22926), although the posterior extremities of these bones
are less noticeably upturned.
The missing lachrymal was lodged in the gap between
the antorbital portion of the supraorbital process and the
apophysis of the maxillary.
The temporal fossa is relatively small, shortened antero-
posteriorly, and bounded by the squamosal and its zygo-
matic process posteriorly and ventrally, and by the frontal
dorsally and anteriorly. On one skull (USNM 14729) the
almost vertical sutural contact of the ventrally situated
alisphenoid with the squamosal at the rear is quite distinct.
Careful examination of the temporal fossae of three skulls
did not reveal the boundaries or relations of the parietal
bone on the outer wall of the braincase. On the skull of the
young Physeter catodon the parietal is in contact ventrally
with the alisphenoid and meets the frontal anteriorly;
dorsally it seems to be intimately coalesced with the frontal
and may possibly be in contact posterodorsally with the
external border of the supraoccipital. Similar relationships
of these bones seem to exist on the Orycterocetus skulls. The
parietal, however, is excluded from the top of the cranium
behind the supracranial basin.
Abel (1905, p. 72) states that on the skull of Thalassocetus
antwerpiensis the parietals are visible on the dorsal crest
between the supraoccipital and the frontals. Judging from
the relations of the cranial bones of the Orycterocetus skull
it would appear that it is the posterior border of the frontal
that is exposed between the overriding maxillary and the
supraoccipital. If this is the correct interpretation, the
parietal is shut off from the vertex and restricted to the
temporal fossa. The alisphenoid extends forward to the
supraorbital process of the frontal and contributes the pos-
terior border of the optic furrow.
Both zygomatic processes are essentially complete on the
largest skull (USNM 22926). They are relatively slender,
but thickened dorsoventrally, with a curved concave
glenoid articular surface. If not actually in contact, the
postorbital projection of the supraorbital process at least
overhung the anterior end of the zygomatic process. The
actual contact between the exoccipital and the squamosal
is revealed quite distinctly when this region is viewed from
the side.
The rostrum is exceptionally well preserved on one speci-
men (USNM 22931). It is rather deep near the middle of
its length (pl. 29, top), the maximum depth there slightly
exceeding that of the proximal end. Commencing at the
level of the fifteenth alveolus counting backward from the
anterior end of the maxillary, the outer border of that bone
becomes progressively thinner toward the antorbital notch.
The maxillary itself, however, increases in vertical diameter
anteriorly on the proximal half of the rostrum, and attains
its maximum depth at the level of the twelfth alveolus
counting backward from the anterior end of this bone.
From this point forward the lateral surface of the rostrum
becomes more nearly vertical and the dorsoventral diameter
of the maxillary diminishes while that of the premaxillary
increases. Anteriorly the premaxillary (pl. 28, bottom)
projects forward beyond the maxillary, contributing the
extremity of the rostrum, on which three teeth were present
in the same number of very shallow alveoli.
VENTRAL VIEW.—The general contour of the ventral
aspect of the Calvert physeteroid skull (pl. 23) is somewhat
pentagonal. As contrasted with the skull of Diaphorocetus
poucheti (Lydekker, 1894, pl. 3, fig. 1), the more obvious
distinctive characteristics of the ventral portion of the
Calvert skull (fig. 31) are the more elongated zygomatic
processes, wider and possibly more closely approximated
hamular processes of the pterygoids, more protuberant
occipital condyles, larger antorbital maxillary notches,
54 UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 2
FicurE 31.—Ventral view of skull, USNM 22926, of Orycterocetus
crocodilinus, with anterior end of rostrum, incomplete orbital
border of right supraorbital process, occipital condyles, and
alveoli restored. Abbrs.: Al., alisphenoid; ant.n., antorbital
maxillary notch; ap.max., maxillary apophysis; Bo., basioccip-
ital; Bs., basisphenoid; C., occipital condyle; d., depression
in front of area for attachment of spongy mass; Ex.oc., exoccipi-
tal; f., oval depression on anterior glenoid articular surface;
f.max., ventral aperture of infraorbital system; Fr., frontal;
h.pt., hamular process of pterygoid; j.n., jugular incisure; |.pr.,
lateral descending falcate plate of basioccipital; Max., maxillary;
Pal., palatine; pgl., postglenoid process of zygoma; Pmx., pre-
maxillary; pr.pa., paroccipital process of exoccipital; Pt., ptery-
goid; pt. p., vertical plate of pterygoid; s.or.pr., supraorbital
process of frontal; Sq., squamosal; Vo., vomer; zyg., zygomatic
process of squamosal.
= ©O@oo Gio) OOG000
RN
.
ae OOOO COCEC909%
90°
S006
>
a
2
ani.n.
ap. max.
pr.pa.
THE SPERM WHALE ORYCTEROCETUS 55
and alveoli for maxillary teeth not extended as far toward
the base of the rostrum. The right lachrymal is retained
on the skull of Diaphorocetus poucheti attached to or wedged
in between the apophysis of the maxillary and the antorbital
portion of the supraorbital process. Seventeen alveoli for
the teeth (pl. 28 bottom) implanted in each maxillary
are readily discernible (USNM 22931). None of the
alveoli exceed 15 mm. in depth and most alveoli are
somewhat shallower, irregularly shaped and enclosed
within cancellous or spongy bone. The four posteriormost
alveoli, fourteenth to seventeenth inclusive counting
backward from the anterior end of the palatal surface of
the maxillary, are rather shallow and not sharply defined.
Behind the posteriormost alveolus in the left maxillary and
internal to it is a row of six shallow circular depressions
for lodging the crowns of corresponding mandibular
teeth. Four similarly located circular depressions are
present on the right maxillary. The absence of similar
depressions for mandibular teeth on the anterior palatal
surface may possibly indicate that the mandible did not
extend forward to the extremity of the rostrum. Presum-
ably not more than three rather small, shallow alveoli
were present in each premaxillary, the anteriormost
alveolus on each side being the deepest. These alveoli
must have lodged a very short root of a small nonfunctional
tooth. The full complement of teeth on each side of the
palatal surface of the rostrum is thus 20 teeth. On the
constricted anterior portion of the rostrum the teeth were
implanted along the outer border of the maxillary in
distinct and fairly equally spaced alveoli, the interval
between them varying from 7 to 15 mm. These alveoli
do not follow the external border of the maxillary proximally
beyond the narrowed distal portion of the rostrum, but
do nevertheless diverge as the basal palatal portion of
each maxillary increases in width. The location of the
posterior maxillary alveoli on the skulls of Jdzorophus
(Apenophyseter), Scaldicetus and Physeterula is at present
unrecorded.
On the skull of the largest individual (USNM 22926),
the left maxillary tooth row terminates 90 mm. in front of
the anterior end of the left palatine, or 160 mm. in front
of the hinder margin of the antorbital maxillary notch.
The four hindermost teeth were implanted in relatively
shallow alveoli in the left maxillary; the alveoli located
anterior to these four posterior alveoli become progressively
deeper and slope obliquely inward and backward from the
alveolar margin. No circular depressions for lodging the
crowns of mandibular teeth were noted on the palatal
surface of either maxillary.
The ventral or palatal surface of the rostrum (pl. 23)
is formed largely by the maxillaries. Proximally the
internal edges of the maxillaries become separated by the
narrow keel of the vomer slightly behind the level of the
anterior ends of the palatines and then spread apart
distally to permit the premaxillaries to be visible between
them. The vomer can be observed for a distance of
200 mm. between the maxillaries on the palatal surface of
two skulls (USNM 22926 and USNM 22931) and for a
somewhat variable distance on other skulls before it is
entirely shut off on the anterior half of the rostrum by the
close longitudinal contact of the opposite premaxillaries.
The large single orifice for the infraorbital system is located
internally to the antorbital notch on each maxillary
(USNM 22926). Two ventral orifices for the infraorbital
system, one anterior to the level of the antorbital maxillary
notch and the other posterior to the level of this notch are
present on the palatal surface of each maxillary of the
Californian Miocene sperm whales, Idiophyseter merrtami and
Aulophyseter morricez.
Anteriorly, each premaxillary first becomes visible as a
narrow strip on the palatal surface of the rostrum between
the opposite maxillaries and the narrowly exposed keel of
the vomer at the level of the anterior third of the latter.
The lachrymal bone has been dislodged and lost on all of
these Calvert skulls. In its original position it was lodged in
the narrow groove between the apophysis of the maxillary
and the antorbital portion of the supraorbital process and
apparently conformed to that of Dzaphorocetus pouchets
(Lydekker, 1894, pl. 3, fig. 1).
The palatine bones were fairly well preserved on the
largest skull (USNM 22926), but are missing on the others.
Each palatine is mortised into the ventral surface of the
corresponding maxillary and projects forward considerably
beyond the level of the large infraorbital system aperture.
The anterior ends of the palatine bones are obtuse and the
external margins are convexly curved. The palatines are
overlapped posteriorly by the pterygoids. The relations
of the palatines to the surrounding bones were thus essen-
tially the same as on the skull of a young Physeter catodon
(Kellogg, 1925, pl. 6, fig. 3).
The pterygoids meet on the midline and their hamular
processes prolong the palate backward. The hamular
processes (pl. 23) are large, relatively broad and completely
conceal the nasal passages from a ventral view. The ex-
ternal margin of each hamular process does not overhang
the vertical plate of the corresponding pterygoid. Both
hamular processes project backward beyond the level of
the furrow for the optic nerve. The internal edges of the
hamular processes are in contact for most of their length,
but diverge slightly behind the level of the nasal passages,
forming obliquely truncated posterior ends. The vertical
plate of each pterygoid merges posteriorly with the lateral
descending falcate plate of the basioccipital.
The posterior end of the vomer is horizontally widened
and overrides the basisphenoid and between the nasal
passages forms the trough in the posterior end of which the
56 UNITED STATES NATIONAL MUSEUM BULLETIN
presphenoid is lodged. The vomer contributes a portion
of the lower half of the internal and posterior wall of each
nasal passage, meeting the ethmoid dorsally.
The median region of the basicranium is bounded laterally
by the deep vertical plates of the pterygoids (pl. 23) and
posteriorly by the adjoining descending falcate plates of the
basioccipital. The median basicranial region is relatively
wide.
The flangelike falcate plates of the basioccipital descend
obliquely and are directed outward and backward, but not
projecting posteriorly beyond the occipital condyles (USNM
22926). Each falcate plate is thickened near its truncated
extremity. The basioccipital is a relatively short bone,
ankylosed anteriorly with the basisphenoid, and terminated
posteriorly by the two condyles.
Between the descending falcate plate of the basioccipital
and the thickened paroccipital process is the deep jugular
incisure. The jugulo-acoustic funnel is bounded posteriorly
by the exoccipital, internally by the basioccipital and an-
teriorly by the alisphenoid.
The horizontal flattening of the ventral surface of the
alisphenoid and the adjacent surface of the squamosal
seems to have resulted from the general widening of the
basicranium (USNM 14729). The alisphenoid is relatively
large and expanded horizontally. This bone is bounded
anteriorly by the supraorbital process of the frontal, suturally
united and in squamous contact posteroexternally with the
squamosal, and in contact posterointernally with the
basisphenoid and basioccipital. The horizontal expansion
of the alisphenoid and the absence of a projecting glenoid
process of the squamosal has as in other physeteroids
resulted in the elimination of the tympanoperiotic recess
which is a characteristic feature of delphinoids. The
periotic and tympanic bones are thus excluded from the
wall of the cranial cavity. No external reduplication of
the pterygoid was developed on this Calvert sperm whale
skull and this in conjunction with the closure of the area
occupied on most odontocete skulls by the tympanoperiotic
recess seem to represent a constant physeteroid basicranial
characteristic. This basicranial modification was accom-
panied by the disappearance or relocation of some of the
posterior foramina. The optic furrow (pl. 26) terminates
internally on the ventral surface and the optic nerve makes
its exit through a small foramen in the anterior wall of the
braincase. The sphenoid fissure (USNM 14730) is bounded
by the vertical plate of the pterygoid ventrally, by the
alisphenoid posteriorly, and by the orbitosphenoid an-
teriorly and externally.
The foramen ovale pierces the internal portion of the
alisphenoid and its ectal orifice is located near and external
to the base of the more or less vertical plate of the pterygoid
(USNM 22926 and USNM 14729). The foramen ovale
for the mandibular branch of the trigeminal nerve on the
247 PART 2
young skull (USNM 22930) by the progressive closure of
the elongated notch or fissure is now cut off from the edge
of this bone; but its earlier condition is shown by the deep
groove that marks the former position of the notch. Al-
though the foramen ovale is located at the end of the
conspicuous longitudinal notch at the posterior margin
of the alisphenoid on the fetal Physeter skull, on the skull
(pl. 29 bottom) of this very young Calvert Miocene
physeteroid this elongated notch seemingly at an earlier
growth stage was situated between the inner edge of the
alisphenoid and the basioccipital.
The jugulo-acoustic funnel opens into the cranial cavity
and is concealed from a ventral view by the descending
falcate plate of the basioccipital. The deep jugular incisure
is located external to this cranial opening. On the
basicranium (pl. 29 bottom) of the very young Calvert
sperm whale (USNM 22930) the oblique course of the
jugulo-acoustic funnel is exposed, showing that it is directed
forward and upward between the exoccipital, the basioc-
cipital and the inner margin of the alisphenoid. In this
region the base of the vertical plate of both pterygoids has
been dislodged, exposing a narrower channel and foramen
for the internal carotid, measuring 6 mm. in diameter,
internal to and parallel below with the jugulo-acoustic
funnel. This foramen pierces the basisphenoid in the
region where it is embraced by the base of the vertical
plate of the pterygoid. The jugulo-acoustic funnel opens
into the cranial cavity on this young fossil basicranium
some 53 mm. anterior to the articular face of the paroc-
cipital process. The articular surface on the paroccipital
process (pl. 23) of the exoccipital for attachment of the
stylohyal is well defined on the largest skull (USNM 22926).
The squamosal contributes a relatively small area of
the external wall of the braincase. A long curved irregular
suture marks the union of the squamosal with the alisphe-
noid on the basicranium of the young fossil skull (USNM
22930). The squamous overlap of the squamosal by the
alisphenoid is clearly delimited in the cranial cavity of this
young fossil skull. Viewed from below the zygomatic
process is rather slender; its glenoid articular surface is
shallowly concave transversely, and concavely curved
anteroposteriorly, but is not set off from the rest of the
squamosal by an elevated internal margin. At the anterior
end (fig. 31) of the ventral articular surface of the zygomatic
process there is a distinct elliptical or elongated oval de-
pression (15><40 mm.) whose function is not readily ap-
parent. The glenoid articular surface of the zygomatic
process is also fairly well defined on the young Calvert
fossil skull. The postglenoid projection of the zygomatic
process is rather short and thin. The squamosal is rather
deeply excavated postero-internally to the glenoid articular
surface of the zygomatic process to constitute a shallow
THE SPERM WHALE ORYCTEROCETUS
depression in front of the area for attachment of the spongy
osseous mass associated with the tympanic bulla. No
remnant persists of the falciform process of the squamosal
that articulated in other odontocetes with the alisphenoid.
Posteriorly, the squamosal abuts against the exoccipital,
whose posterior face curved convexly outward and forward.
Measurements in millimeters of the young Calvert sperm
whale skull (USNM 22930) are as follows: Greatest
breadth of skull across zygomatic processes, 292; greatest
height of skull (basisphenoid to transverse supraoccipital
crest), 215-+; greatest breadth of right premaxillary op-
posite narial choanae, 58; greatest anteroposterior diameter
of right supraorbital process at extremity, 50; least breadth
of supraoccipital between temporal fossae, 205; greatest
length of zygomatic process, 66; and distance across skull
between outer margins of exoccipitals, 268.
Measurements (in mm.) of the skulls USNM 22926
(Zone 13, south of Parker Creek, Md.), USNM 14730
(Zone 12, south of Parker Creek, Md.), and USNM 14729
(Zone 11, south of Randle Cliff beach, Md.) are as follows:
USNM USNM USNM
22926 14730 14729
Total length as preserved (condyles 724+ 631+ 750+
to tips of premaxillaries)
Total length estimated (condyles to 830+ = =
tips of premaxillaries)
Length of rostrum as preserved 425+ 384 500
(antorbital notches to extremity)
Breadth of rostrum at antorbital 343 303 285
notches
Breadth of rostrum at enlargement 350 298 202
in front of antorbital notches
Greatest breadth of skull across 445 395 383
maxillary apophyses
Greatest breadth of skull across 485 — 478+
zygomatic processes of squamosals
Vertical height of skull (basi- 308 271 310
sphenoid to transverse crest)
Vertical height of skull (hamular 353 = =
process of pterygoid to transverse
crest of supraoccipital)
Greatest width of maxillary from a 225 205 195
ventral view (internal margin to
maxillary apophysis)
Greatest length of right premaxil- 640 580 637
lary as preserved, in a straight line
Greatest breadth of right premaxil- II 80 100
lary at level of narial choanae
Greatest breadth of right premaxil-
lary posterior to narial choanae
Greatest anteroposterior diameter 115
of supraorbital process of frontal
at extremity
225 149
103 =
Greatest dorsoventral diameter of
preorbital portion of supraorbital
process of frontal
Elevation of lateral crest of supra-
cranial basin above orbit
Least breadth of supraoccipital be-
tween temporal fossae
Distance from summit of transverse
crest of supraoccipital to upper
margin of foramen magnum
Height of foramen magnum
Transverse diameter of foramen
magnum
Greatest distance between outside
margins of occipital condyles
Greatest vertical diameter of occi-
pital condyle
Greatest transverse diameter of oc-
cipital condyle
Distance across skull between outer
margins of exoccipitals
Distance between anterior margin
of maxillary apophysis and pos-
terior face of condyle
Distance across basicranium be-
tween opposite foramen ovale
Length of vomer exposed on ventral
face of rostrum
Greatest length of right palatine
Greatest breadth of right palatine
Greatest length of right pterygoid
including hamular process
Greatest length of zygomatic
process
Greatest diameter of right narial
choanae
Greatest diameter of left narial
choanae
Apex or crest of supraoccipital to
extremity of rostrum, as preserved
Right antorbital notch to apex or
crest of supraoccipital shield
(medially)
Inner margin of right premaxillary
to inner margin of antorbital
notch
Inner margin of right premaxillary
to outer margin of maxillary
apophysis
Distance between outside margins
of opposite maxillary apophyses
Distance between outside margins
of opposite preorbital portions of
supraoccipital processes
Distance between opposite notches
for jugular leash
57
USNM USNM USNM
22926
36
294
207
251
63
81
150
107+
38
456
397
150
162
150
67
130
145
24
53
660+
359
158
203
446
456
245
14730
37
170
218
196
60
66
122
34
314
14729
661+
277
130
183
200
58 UNITED STATES NATIONAL MUSEUM BULLETIN
Teeth
Seventeen teeth were lodged in each maxillary in distinct
alveoli, three were present on each premaxillary, and an
unknown number in each mandible. Sixteen teeth (pl.
30 top) were associated in the sandy clay enveloping the
most mature skuJl (USNM 22926) and the posterior end
of the left mandible. There is no certainty that these
16 teeth indicate either immaturity or that they were
once embedded in the upper jaw. ‘The skull of the Recent
sperm whale (Physeter catodon) carries from one to eleven
vestigial or very small curved teeth on each side of the
upper jaw. ‘These small teeth of Physeter are either com-
pletely hidden from a palatal view or their tips only cut
through the gum. Larger and more robust teeth (pl.
30, figs. 11-14) characterized by annular lines of growth
and an outer layer of cementum have also been recovered
from the Calvert formation. These unquestionably repre-
sent teeth of mature individuals and are quite probably
mandibular teeth.
The 16 teeth associated with the skull (USNM 22926)
and the four isolated teeth (USNM 22933) are very similar
in general conformation. These slender strongly curved
teeth vary in length from 45 mm. to 78 mm. The general
conformation of one of these teeth is an elongated curved
cone, with either slightly flattened or longitudinally grooved
sides, and with the posterior face less convex than the
anterior curved surface. Three of these slender teeth
(USNM 22933) and one associated with the skull (USNM
22926) have a completely closed pulp cavity at the end
of the root (pl. 30, figs. 9-10). At the open base of the
root of the other teeth, the funnellike pulp cavity which
extends distally for one-fourth to one-third of the length
247 PART 2
of the root, is bounded by a very thin and fragile outer
wall. Seven of these teeth (pl. 30, figs. 6, 7, 8, 9, 10)
have an attenuated distal or apical end, but no trace of
enamel. Four of these teeth have worn distal ends (pl.
30, figs. 1, 3, 4, 5). There exists no distinction between
the apical portion which would be regarded as the crown
and the root. Annular lines of growth are not visible on
these slender teeth.
The largest tooth (pl. 30, fig. 12) recovered from the Cal-
vert formation measures 92 mm. in length, while its greatest
diameter (20.5 mm.) is at the base which is open, the pulp
cavity extending distally for half the length of the root.
The root is ovoidal in transverse section at the base. This
tooth has retained some of its outer layer of cementum and
displays annular rings of growth, but no enamel on the tip
or crown. A portion of the tip is missing. The root is also
indistinctly fluted or ridged longitudinally and is much less
noticeably curved from end to end than the more slender
teeth. This (USNM 22935) may possibly be a mandibular
tooth.
The next largest tooth (USNM 22934) is strongly curved
from end to end, rather deeply longitudinally fluted or
grooved, and exhibits fine annular lines of growth. The
outer layer of cementum is retained only on the proximal
end and the pulp cavity is rather short, extending distally
less than one-fourth the length of the root. The apical or
crown end is worn and is ovoidal in transverse section; a
small area on the tip is blackish and shining. At its base
the root is more noticeably triangular in cross section. This
tooth (pl. 30, fig. 13) measures 89 mm. in length, and its
greatest diameter at the base is 15.5 mm. Some variation
obviously exists in the length of the pulp cavity, which on
the type tooth of Orycterocetus crocodilinus according to Cope
USNM USNM USNM USNM USNM USNM USNM
Wepsia rete of reat 22926, 22926, 22926, 22926, 22926, 22926, 22926,
pl. 30 pl. 30 pl. 30 pl. 30 pl. 30 pl. 30 pl. 30
fg. 8 fig. 7 fig. 6 Sig. 5 Sig. 4 fig. 3 fig. 2
Greatest length of tooth as preserved in a straight 68 62 56 53 5I 52.7 49.6
line
Anteroposterior diameter of most expanded portion 7-5 9.5 8.8 10 8.9 8.9 8.3
of root
Transverse diameter of most expanded portion of 7-2 9 8.5 8 Tea 8 7-7
root
USNM USNM USNM USNM USNM USNM USNM
Measurements of Teeth: sae 22933» 22933» 22034 22939: 1158, pica
pl. 30 pl. 30 pl. 30 pl. 30 pl. 30 pl. 30 pl. 30
fig.t Sig. 10 fig. 9 fig.13 fig.12 fig. 14 fg.7
Greatest length of tooth as preserved in a straight 44.7 78.6 68.3 89 92 70 64.5
line
Anteroposterior diameter of most expanded portion 9.5 II.5 10. 5 15.5 20.5 18. 4 13.7
of root
Transverse diameter of most expanded portion of 8.5 10.6 9.2 14 16 17-5 10. 7
root
THE SPERM WHALE ORYCTEROCETUS 59
(1868, p. 145) extends distally for two-thirds of the length
of the tooth.
Another tooth (USNM 1158) from the Miocene Choptank
formation overlying the Calvert formation probably belongs
to this species of sperm whale. The pulp cavity at the
base of the root is closed, the thin annular lines of growth
on the dentine are quite distinct, the outer layer of cemen-
tum is missing and the apical end or crown (pl. 30, fig. 14)
-is worn. The length of this tooth is 70 mm., and the
greatest transverse diameter near the tip is 17.5 mm.
All of the teeth thus far recovered from the Calvert Mio-
cene formation are less than half the size of those of Scaldi-
cetus careitt. Rugose striated enamel on the crowns in part
characterizes the teeth of Scaldicetus caretti and S. grandis.
The skull of Physeterula dubusti was considerably larger than
that of Orycterocetus crocodilinus, seemingly at least a third
or more longer, and the mandibular teeth are also large.
The teeth of this Antwerp species lack enamel on the
crowns. The architecture of the skull is largely unknown.
Abel (1905, p. 81) describes the articular surface of the
zygomatic process as large, like that of Physeter, but the
symphysis of the mandibles is shorter. No teeth were
definitely associated with the skull of Thalassocetus antwerpien-
sis. Teeth, however, very similar to those of Orycterocetus
crocodilinus are described and figured by Abel (1905, pp. 73-
74, figs. 9-10). These slender curved teeth have an open
pulp cavity and no enamel, but the dentine at the tip (or
crown) of the teeth is black and shining. Abel suggested
that they may be the teeth of Thalassocetus and also that the
skull may have belonged to a young Scaldicetus.
Measurements (in mm.) of the teeth are tabulated
opposite.
Periotic
One (pl. 31, fig. 3) of the five periotics here described was
associated with the most mature and most completely pre-
served skull. Three of the periotics have the posterior
process worn or eroded to varying degrees. One (USNM
22953) is exceptionally well preserved, possibly owing in
part to its attachment to the corresponding tympanic
bulla. The periotic of the Calvert sperm whale resembles
in essential details that of the Tembler Miocene Aulophyseter
morricet (Kellogg, 1927, pls. 8-9). The various structures of
all described fossil physeteroid periotics are quite similar
and are readily distinguishable from those of other odon-
tocetes, Recent and fossil. The external portion of this
periotic (pl. 32, fig. 2) comprising the anterior and posterior
processes is very dense and heavy; the internal subhemi-
spherical pars cochlearis and pars vestibularis is noticeably
lighter.
The posterior process in an unworn condition (pl. 32,
fig. 3) is characterized by projecting rugosities or spines
that impart an irregular external and anterior emargina-
tion. Fine osseous ridges and grooves radiating outward
from the base or internal margin of the posterior process
mark the area of attachment of this concave surface with
the corresponding surface of the tympanic bulla. This
posterior articular surface is somewhat quadrangular in
outline, the posterior edge being nearly straight. The
anterior and posterior margins of this process on two of
these periotics (USNM 11234 and USNM 22926) are
slightly elevated above the concave articular surface and
the ridges and grooves for attachment to the tympanic
bulla are coarser. The ventrointernal border of the
posterior process projects inward and its free edge con-
tributes the floor of the facial canal for about half of its
length. The dorsal surfaces of the posterior process are
somewhat rugose when unworn. Four of these periotics
(pl. 32) illustrate the variation that may be expected in the
elongation and the shape of the posterior process.
There is a circular rugose or pitted depressed area
(pl. 32, fig. 4) near the middle and on the internal border
of the pars cochlearis on three of these periotics (USNM
11234, 22926 and 22953) behind the embraced accessory
ossicle. The major area of the ventral face of the pars
cochlearts is more or less flattened and slopes toward the
anterior margin, with the most inflated portion in front
of the fenestra rotunda. The internal face of the pars
cochlearis is flattened and almost vertical. From a tympanic
view three apertures are visible and of these the largest is
the fenestra rotunda on the posterior face of the pars
cochlearis. ‘This fenestra is somewhat ovoidal in outline
and is modified to a varying extent by the dimensions of
the connecting aqueduct. The fenestra ovalis is ovoidal
in outline and is situated near the center of the tympanic
face of the periotic. On the outside the fenestra ovalis
(pl. 32, fig. 4) is encircled by a narrow rim which is raised
above the canal for the facial nerve and the fossa for the
stapedial muscle. The foot plate of the small stapes is
securely lodged in the fenestra and remains in place on
one periotic (USNM 22953). A medium-sized internal
aqueduct which leads away from the vestibule and two
minute anteroexternal foramina which connect with the
semicircular canals are visible within the fenestra ovalis.
The minute aquaeduct leading from the foramen singulare
has its aperture near the bottom of the vestibule on the
internal wall and near the anterior angle. The epitympanic
orifice of the aquaeductus Fallopii and the fenestra ovalis are
situated in a depression, although the facial canal leading
backward from the latter is partially concealed from a
ventral view by the projecting ledge for the rather small
circular fossa incudis. Posterior to this Fallopian orifice, the
canal for the facial nerve is open along its whole length,
sloping obliquely downward and curving around the
posterior face of the posterior process (USNM 22953).
Posteriorly, the facial canal forms a boundary for the
60 UNITED STATES NATIONAL MUSEUM BULLETIN 247
large excavated fossa for the stapedial muscle. This
fossa for the stapedial muscle is a rather deep concavity;
the surface for the attachment of the muscle extends
downward on the external face of the pars cochlearis. A
thin-edged crest is developed on the ventroexternal angle
of the cochlear region by the encroachment of the fossa for
the stapedial muscle. Between the fenestra ovalis and the
attachment of the accessory ossicle, there is a deep con-
cavity for the reception of the head of the malleus which
originates beneath the epitympanic orifice of the aquadeuctus
Fallopii and extends downward on the anterior process and
the external face of the pars cochlearis to its tympanic face.
Between the rounded swelling on the base of the anterior
process and the anterior margin of the articular facet on the
posterior process, the ventral surface of the external denser
portion of the periotic is hollowed out, becoming distinctly
grooved as it approaches the fossa incudis. This small
shallow circular fossa is situated at the extremity of the thin
ledge which projects inward below the facial canal. The
crus breve of the incus is lodged in this fossa incudis.
The extremity of the anterior process is obtusely pointed
and truncated, the cerebral face being rugose and irregularly
pitted. The contour of the somewhat pyramidal tuberosity
located external to the epitympanic orifice of the aguaeductus
Fallopii is modified to a varying extent by the presence of
small nodosities. The external face of the anterior process
is rounded off between this tuberosity and the tip of this
process. Anterior to the fossa for the head of the malleus,
the ventral surface of the anterior process is deeply concave
from end to end and more or less flattened from side to side.
A relatively large accessory ossicle (pl. 32, fig. 3) or unciform
process of the tympanic bulla is embraced in this fossa.
This ossicle is preserved intact on two periotics (USNM 22926
and 22953) and detached on one (USNM 10860). This
accessory ossicle is rather large, nearly egg-shaped and
exhibits a longitudinal external groove that marks the line
of ankylosis with the thin delicate plate that is fused with or
PART 2
is a continuation of the external lip of the tympanic bulla
in its normal position this ossicle is embraced by the anterior
process of the periotic along its posterointernal border.
When the accessory ossicle is lodged in its normal position,
it contributes the outer wall of the deep notch between it
and the pars cochlearis.
A rather prominent pyramidal tuberosity (pl. 31, fig. 4)
is present on the outer denser portion of the periotic external
to the cerebral orifice of the aquaeductus Fallopii on two of the
periotics (USNM 11234 and 22926), but is much less
conspicuous on the other two periotics. On all four of
these periotics the anterior process in front of the pars
cochlearis is concavely depressed. From an external view
(pl. 32, bottom) the posterior process is noticeably elongated
in contrast to the rather robust anterior process. The bony
partition between the entrance to the aguaeductus Fallopii and
the more centrally located tractus spiralis foraminosus is some-
what variable in its development (pl. 31, fig. 2). The con-
tour of the rim of the internal acoustic meatus is subpyriform,
although on one periotic (USNM 11234) the rim of the
above described bony partition is almost on a Jevel with
or continuous with the rim of the internal acoustic meatus.
The most anteriorly located orifice on the cerebral face
of the pars cochlearis is that of the aquaeductus Fallopii (pl. 31,
fig. 1) through which passes the facial nerve to emerge on
the tympanic or ventral face slightly anterior to the fenestra
ovalis. At the bottom of the large and relatively deep
internal acoustic meatus is located the tractus spiralis foram-
inosus and the minute foramen centrale. The small
compressed foramen sigulare is located on the external wall
of this meatus about half way between the rim and the bot-
tom. The orifice of the aquaeductus vestibult is located outside
of and posterior to the rim of the internal acoustic meatus,
in a narrow slitlike depression or fossa (pl. 31, fig. 2). The
cerebral orifice of the aquaeductus cochleae is also located
posterior to the meatus, and is smaller than the orifice of
the aquaeductus Fallopii. The interval between the orifice
USNM
USNM USNM USNM USNM
Measurements of Periotics: 11234, 22926, 22052, 22953; 10860,
Right Left Left Right Right
pertotic pertotic pertotic pertotic pertotic
Breadth of periotic at level of fenestra ovalis (as measured from external face 24 25. 4 20.8 23.6 21.8
above excavation to internal face of pars cochlearis)
Greatest length of periotic (tip of anterior process to tip of posterior process) 37.8 41.3 42 43.8 33-6
Greatest dorsoventral depth of periotic (as measured from most inflated por- T6597, 18. 4. 15. 4 17-5 16.2
tion of tympanic face of pars cochlearis and external excavation to most
projecting point on cerebral face)
Distance between fenestra rotunda and tip of anterior process 19 22.6 24.8 23.8 22
Distance between fenestra rotunda and tip of posterior process 18.3 22.5 28.5 21.2 14.5
Distance between epitympanic orifice of aquaeductus Fallopit and tip of 17.2 17) 16.7 18.7 16.3
anterior process
THE SPERM WHALE ORYCTEROCETUS
of the aquaeductus cochleae and that for the aquaeductus
| vestibuli varies from 2.0 to 3.3 mm. As shown by the table
| of measurements the five periotics exhibit relatively slight
| dimensional differences, but one (USNM 22952) is abnormal
in some respects (pl. 32, fig. 1).
The right and left periotics described and figured by
| Abel (1902, pp. 121-122, fig. 19; pl. 17, figs. 11-12) un-
questionably belonged to one of the Miocene sperm whales
| (Scaldicetus, Physeterula, or Thalassocetus) whose skeletal re-
| mains were excavated in the deposits in the Antwerp basin.
| As a result of fortuitous proximity they were associated
with a skull of Eurhinodelphis longirostris by Abel. ‘The char-
| acteristics of the periotic bones of Eurhinodelphis are known
_ with certainty, inasmuch as these ear bones have been found
_ attached in situ to Calvert Miocene skulls belonging to this
genus. These Antwerp periotics are not markedly unlike
those of Orycterocetus and judging from the measurements
_ given by Abel they are approximately the same size as one
Calvert periotic (USNM 11234).
Measurements (in mm.) of the periotics are tabulated
_ opposite.
Tympanic Bulla
No tympanic bulla was found associated with any of the
Calvert sperm whale skulls in the national collections.
Fortunately, a right tympanic bulla (USNM 22953) was
_attached to a right periotic when it was discovered in the
block of sandy clay which had fallen from the face of the
cliff. As is usually the case tympanic bullae of the fossil
cetaceans are incomplete in one or another respect when
found. The anterior end of the thin brittle outer lip which
arches over the involucrum and the slender and rather
delicate processus gracilis of the malleus normally attached
to the sigmoid process, as well as the anterior process which
forms the thin osseous connection with the accessory ossicle
are missing.
In ventral aspect (pl. 31, fig. 6) the bulla is abruptly
widened behind the middle of its length, its posterointernal
end is rather angular and its posteroexternal end is rounded
off. A broad shallow groove traverses the median area of
the posteroventral surface of the bulla.
The dorsal aspect of the bulla (pl. 31, fig. 7) is character-
ized in part by the sinuous curvature of the rather narrow
involucrum and the relatively large and wide backwardly
projecting posterior pedicle. The anterior end of this
bulla is not sufficiently complete to indicate the size and
contour of the anterior outlet or tympanic aperture for the
eustachian canal. The involucrum is widest posteriorly,
constricted near the middle of its length and attenuated
anteriorly. The dorsal surface of the involucrum is less
convex posteriorly than anteriorly and faintly rugose, but
anteriorly it is more noticeably convex from side to side
and internally descends abruptly into the tympanic cavity.
61
The overarching thin outer lip of this bulla (pl. 31, fig. 7),
when complete, curved from end toend. The thin anterior
process of the bulla which forms the connection with the
accessory ossicle is broken off at the level of the edge of the
thin outer lip, and remains attached to this ossicle on the
periotic (pl. 32, fig. 3). The large posterior pedicle pro-
jects upward, outward and backward; the contiguous
portion of the outer lip and the involucrum furnish the
supporting structures. No narrow vertical fissure separates
the portion of this pedicle (pl. 31, fig. 5) which arises from
the involucrum from the portion which projects from the
outer lip. The articular surface (pl. 31, fig. 7) on this
posterior pedicle is unusually broadened, emarginate on
its edges and creased by outward radiating ridges and
grooves. A distinct dorsoventral ridge marks the posterior
limit of the external face of the bulla and terminates dorsally
on the short posterior conical apophysis or tuberosity ad-
jacent to the sigmoid process. This sigmoid process is
twisted to the extent that its extremity is almost transverse
to the long axis of the bulla. The groove on the outer lip
of the bulla anterior to the sigmoid process is rather broad
and is continuous with the median depressed area on the
posterior portion of the ventral face of the bulla. The
anterior face of the terminal portion of the sigmoid process
is hollowed out and the posterior face is somewhat curved
or convex.
The laminated spongy osseous mass (USNM 22953)
found associated with the right periotic and attached tym-
panic bulla is unusually light in weight for a bone of this
size. Its dimensions are approximately as follows: greatest
length, 42 mm.; greatest width, 38 mm. These thin plates
(pl. 31, fig. 8) are pressed together more compactly at the
enlarged extremity than at the base where some are sepa-
rated from adjacent plates by an interval of 1 to 2 mm.
Flower (1868, p. 321) has described a similar laminated
structure for the Recent sperm whale (Physeter catodon)
where the rather large mass of thin plates is held together
through their attachment to the mastoid or posterior proc-
ess of the tympanic bulla. Furthermore, the posterior
edge of each squamosal, which is visible between the ex-
occipital and the postglenoid process, has a laminated
character, the ridges and grooves on the contiguous surface
fitting into those of this laminated mass.
The edge of the squamosal exposed between the ex-
occipital and the postglenoid process of the skull of Oryctero-
cetus (USNM 22926) exhibits a similarly laminated con-
dition. Thus this condition or peculiar modification for
the attachment of the petrotympanic to the skull had been
developed certainly by Calvert Miocene time. Apparently,
judging from the illustration of the skull of the lower Mio-
cene Patagonian Diaphorocetus poucheti (Lydekker, 1894,
pl. 3, fig. 1) the hinder edge of the squamosal exhibits a
laminated appearance.
62 UNITED STATES NATIONAL
Measurements (in mm.) of the right tympanic bulla of
USNM 22953 are as follows:
Greatest anteroposterior diameter without 31.5
posterior pedicle, as preserved
Greatest dorsoventral diameter on internal side 14
Greatest transverse diameter 21.6
Greatest dorsoventral diameter on external side 23
(ventral face to tip of sigmoid process)
Mandible
A relatively small fragment of the posterior end of the
left mandible was associated with one skull (USNM 22926).
This portion of the ramus is characterized by a relatively
thin fragile shell; the dorsal and ventral borders are in-
complete. The external face of this portion of the ramus
is convex; the internal face is concave and the lower
MUSEUM BULLETIN 247 PART 2
border is bent inward. The condyle (53+ x 41 mm.) is
located at the posteroventral angle of the ramus; its ventral
angle seemingly does not project beyond the level of the
ventral face of the mandible. The major axis of the
condyle is oblique to the vertical axis of the hinder end of
the ramus. The external border of the condyle is rather
thick and rounded, projecting outward beyond the outer
face of this portion of the ramus, in contrast to its somewhat
thinner and sharp-edged internal and ventral margins of
the internal face. The condyle as a whole becomes progres-
sively thinner toward the ventral margin of the ramus; its
posterior articular surface is convex and its anterior face
strongly concave. From the curvature of the thin outer
wall it would appear that a large opening for a dental
canal was located on the inside of the posterior portion of
the ramus. The condyle of the Recent Physeter catodon is
more noticeably elongated and its major axis more nearly
vertical and not twisted inward.
BIBLIOGRAPHY
ABEL, OTHENIO
1902. Les dauphins longirostres du Boldérien (Miocéne supérieur) des environs d’Anvers.
Mém. Mus. Hist. Nat. Belgique, Bruxelles, vol. 2, pp. 101-188, figs. 18-20, pls. 11-18.
1905. Les Odontocétes du Boldérien (Miocéne supérieur) d’Anvers. Mém. Mus. Hist. Nat.
Belgique, Bruxelles. vol. 3, 155 pp., 27 figs.
CaBRERA, ANGEL
1926. Cetdceos fésiles de La Plata. Rev. Mus. La Plata, Buenos Aires, vol. 29, pp. 363-411,
19 figs.
CasE, ERMINE COWLEs
1904. Cetacea, in W. B. Clark, Systematic paleontology of the Miocene deposits of Maryland.
Maryland Geol. Surv., Miocene, pp. 1-56; atlas, pls. 10-25.
Corr, EDwARD DRINKER
1868. An addition to the vertebrate fauna of the Miocene period, with a synopsis of the
extinct Cetacea of the United States. Proc. Acad. Nat. Sci. Philadelphia, vol. 19
(1867), no. 4, pp. 138-156. Mar. 10, 1868.
FLower, WILLIAM HENRY
1868. On the osteology of the cachalot or sperm whale (Physeter macrocephalus). Trans. Zool.
Soc. London, vol. 6, pt. 6, pp. 309-372, 13 figs., pls. 55-61.
Gervais, PAUL
1848-1852. Zoologie ou paléontologie frangaises (animaux vertebrés) ou nouvelles recherches
sur les animaux vivants et fossiles de la France, Paris, vol. 1, text. pp. vili+271;
vol. 2, explanation of plates, 142 pp.; vol. 3, atlas, 80 pls.
KELLOGG, REMINGTON
1925. Two fossil physeteroid whales from California, in Additions to the Tertiary history of
the pelagic mammals of the Pacific Coast of North America. Carnegie Inst. Wash-
ington Publ. 348, pp. 1-34, pls. 1-8. April 1925.
1927. Study of the skull of a fossil sperm whale from the Temblor Miocene of southern Cali-
fornia, in Additions to the paleontology of the Pacific Coast and Great Basin regions
of North America. Carnegie Inst. Washington Publ. 346, pp. 3-34, pls. 1-9,
Nov. 3, 1927.
THE SPERM WHALE ORYCTEROCETUS
Lewy, JOsEPH
1853. [Observations on extinct Cetacea.] Proc. Acad. Nat. Sci. Philadelphia, vol. 6 (1852-
53), pp- 377-378. August 1853.
1869. The extinct mammalian fauna of Dakota and Nebraska, including an account of some
allied forms from other localities together with a synopsis of the mammalian remains
of North America. Journ. Acad. Nat. Sci. Philadelphia, ser. 2, vol. 7, 472 pp., 30 pls.
LYDEKKER, RICHARD
1894. Contributions to a knowledge of the fossil vertebrates of Argentina. II. Cetacean
skulls from Patagonia. Anal. Mus. La Plata, vol. 2 for 1893, pp. 1-13, 5 pls.
April 1894.
Moreno, Francisco P.
1892. Lijeros apuntes sobre dos géneros de cetdceos fosiles de la Republica Argentina. Rev.
Mus. La Plata, vol. 3, pp. 393-400, pls. 10-11.
Owen, RICHARD
1846. A history of British fossil animals and birds. London, pp. xlvi-+-560, 236 figs.
Van BENEDEN, PIERRE JOsEPH; and GERVAIs, PAUL
1868-1879. Ostéographie des cétacés vivants et fossiles comprenant la description et icono-
graphie du squelette et du systtme dentaire de ces animaux ainsi que des documents
relatifs A leur histoire naturelle. Paris, text, pp. vili-+634; atlas, pls. 64.
63
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IU.S. NATIONAL MUSEUM BULLETIN 247, PLATE 1
DORSAL VIEW OF SKULL, USNM 11976, PELOCETUS CALVERTENSIS
755—-999—65 6
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE
VENTRAL VIEW OF SKULL, USNM 11976, PELOCETUS CALVERTENSIS
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 3
LEFT JUGAL BONE AND RIGHT TYMPANIC BULLA, USNM 11976, PELOCETUS
CALVERTENSIS
1, Dorsal view of jugal; 2, lateral view of jugal; 3, external view of right tympanic bulla; 4, dorsal
view of right tympanic bulla; 5, posterior view of atlas (USNM 23059).
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 4
10
6
CERVICAL VERTEBRAE, USNM 11976, PELOCETUS CALVERTENSIS
1-5, Anterior views: 1, Atlas; 2, axis; 3, fourth cervical; 4, sixth cervical; 5, seventh cervical. 6-10, Lateral views: 6,
Atlas; 7, axis and third cervical, ankylosed; 8, fourth cervical; 9, sixth cervical; 10, seventh cervical.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 5
DORSAL VERTEBRAE, USNM 11976, PELOCETUS CALVERTENSIS
Anterior views: 1, First dorsal; 2, third dorsal; 3, sixth dorsal; 4, second dorsal; 5, fourth dorsal; 6, terminal
caudal.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 6
.
DORSAL VERTEBRAE, USNM 11976, PELOCETUS CALVERTENSIS
1-5, Dorsal views: 1, First dorsal; 2, second dorsal; 3, third dorsal; 4, fourth dorsal; 5, sixth dorsal. 6-10, Lateral views: 6, .
First dorsal; 7, second dorsal; 8, third dorsal; 9, fourth dorsal; 10, sixth dorsal.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 7
4
DORSAL VERTEBRAE, USNM 11976, PELOCETUS CALVERTENSIS
Anterior views: 1, Tenth dorsal; 2, eighth dorsal; 3, eleventh dorsal; 4, seventh dorsal.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 8
DORSAL VERTEBRAE, USNM 11976, PELOCETUS CALVERTENSIS
Dorsal views: 1, Eighth dorsal; 2, tenth dorsal: 3, seventh dorsal; 4, eleventh dorsal.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 9
DORSAL VERTEBRAE, USNM 11976, PELOCETUS CALVERTENSIS
Lateral views: 1, Seventh dorsal; 2, eighth dorsal; 3, tenth dorsal; 4, eleventh dorsal.
755—-999—65——7
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 10
LUMBAR VERTEBRAE, USNM 11976, PELOCETUS CALVERTENSIS
Dorsal views: 1, Third lumbar; 2, fifth lumbar; 3, fourth lumbar, lateral view of neural spine; 4, anterior caudal vertebra, (?) species
(USNM 11976).
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 11
DORSAL VERTEBRAE, USNM 23058, PELOCETUS CALVERTENSIS
1-4, Dorsal views: 1, Ninth dorsal; 2, tenth dorsal; 3, eleventh dorsal; 4, twelfth dorsal. 5-8, Lateral views: 5, Ninth dorsal;
tenth dorsal; 7, eleventh dorsal; 8, twelfth dorsal.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 12
DORSAL VERTEBRAE, USNM 23058, PELOCETUS CALVERTENSIS
Anterior views: 1, Tenth dorsal; 2, ninth dorsal; 3, eleventh dorsal; 4, twelfth dorsal.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 13
LUMBAR VERTEBRAE, USNM 23058, PELOCETUS CALVERTENSIS
1-4, Dorsal views: 1, First lumbar; 2, second lumbar; 3, third lumbar; 4, fourth lumbar. 5-8, Lateral views: 5, First lumbar; 6,
second lumbar; 7, third lumbar; 8, fourth lumbar.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE
8 7 6 5
LUMBAR VERTEBRAE, USNM 23058, PELOCETUS CALVERTENSIS
1~4, Dorsal views: 1, Fifth lumbar; 2, sixth lumbar; 3, seventh lumbar; 4, anterior caudal vertebra (USNM 23059). 5-8, Lateral
views: 5, Fifth lumbar; 6, sixth lumbar; 7, seventh lumbar; 8, anterior caudal vertebra (USNM 23059).
—
4
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 15
I
TERMINAL VERTEBRAE, USNM 23058, PELOCETUS CALVERTENSIS
Anterior views.
U.S. NATIONAL MuSEUM BULLETIN 247, PLATE 16
RIGHT ULNA AND LEFT PERIOTIC, USNM 23059, PELOCETUS CALVERTENSIS
1, External view of right ulna; 2, tympanic view of left periotic; 3, cerebral view of left periotic.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 17
7
CARPAL BONES, USNM 11976, PELOCETUS CALVERTENSIS
1, Pisiforme; 2, carpal, second row; 3, carpal, second row; 4, carpal, second row; 5, carpal, second row; 6, radiale, one-half; 7, ulnare;
8, intermedium; 9, radiale.
BULLETIN 247, PLATE 18
U.S. NATIONAL MUSEUM
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ays ‘A jedavovjour ‘L Syjoy TT] peduwowrour ‘g ystt ‘J pedaeorjour “G Syst ‘Ty pedueowjour “F SyySrx ‘Ty edawowjour “E Sy str ‘Ay pedawovrour ‘zs yoy ‘TT Tedaworjapy ‘1
SISNSLYSATV9 SNLE90713d ‘9/611 WNSM ‘SSNog Ivdyvovlaw
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 19
PHALANGES, USNM 11976, PELOCETUS CALVERTENSIS
1-7, Tentative allocations: 1, Third digit, right; 2, fourth digit, right; 3, third digit, right; 4, second digit, right; 5, fifth digit, right; 6,
fourth digit, right; 7, third digit, right. 8-10, Views of distal epiphyses (USNM 11976): 8 and 9, epiphyses of radii; 10, epiphysis of ulna.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 20
Bones, USNM 11976, PELOCETUS CALVERTENSIS
Tentative identification as sternum.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 21
Riss, USNM 11976, PELOCETUS CALVERTENSIS
1, First rib, left; 2, second rib, left; 3, third rib, right; 4, fourth rib, right; 5, fifth rib, right; 6, sixth rib, right; 7, seventh rib, right; 8,
eighth rib, right; 9, tenth rib, right; 10, eleventh rib, right; 11, twelfth rib, left.
U.S. NATIONAL MusEUM BULLETIN 247, PLATE 22
DORSAL VIEW OF SKULL, USNM 22926, ORYCTEROCETUS CROCODILINUS COPE
U.S. NATIONAL MusEUM BULLETIN 247, PLATE 23
VENTRAL VIEW OF SKULL, USNM 22926, ORYCTEROCETUS CROCODILINUS COPE
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 24
SKULL, USNM 22926, ORYCTEROCETUS CROCODILINUS COPE
Top: Posterior view. Bottom: Lateral view.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 25
DORSAL VIEW OF SKULL, USNM 14730, CRYCTEROCETUS CROCODILINUS COPE
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 26 |
VENTRAL VIEW OF SKULL, USNM 14730, ORYCTEROCETUS CROCODILINUS COPE
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 27
SKULL, ORYCTEROCETUS CROCODILINUS COPE
Top: Lateral view, USNM 14730. Bottom: Posterior view, USNM 14729.
U.S. NATIONAL MUSEUM
RostrRuM, USNM 22931, ORYCTEROCETUS CROCODILINUS COPE
Top: Dorsal view. Bottom: Ventral view.
BULLETIN 247, PLATE 28
EEE
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 29
pr.pa.
ORYCTEROCETUS CROCODILINUS COPE
Top: Lateral view of rostrum (USNM 22931). Bottom: Ventral view of basicranium of young sperm whale (USNM 22930). Abbrs.:
Al., alisphenoid; Bo., basioccipital; c.f., channel and foramen for internal carotid; Ex.oc., exoccipital; f.ovy., foramen ovale; J.A.,
jugulo-acoustic funnel; j.n., jugular incisure; pgl., postglenoid process of zygoma; pr.pa.. paroccipital process of exoccipital; Sq.,
squamosal; zyg., zygomatic process of squamosal.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 30
:
|
14 13 12 11 10 9
LATERAL VIEWS OF TEETH, ORYCTEROCETUS CROCODILINUS COPE
1-8 (USNM 22926); 9 and 10 (USNM 22933); 11 (USNM 22932); 12 (USNM 22935); 13 (USNM 22934); 14 (USNM 1158).
BULLETIN 247, PLATE 31
U.S. NATIONAL MUSEUM
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U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 32
PERIOTICS ORYCTEROCETUS CROCODILINUS COPE
1~4, Tympanic or ventral views: 1, Left periotic (USNM 22952); 2, left periotic (USNM 22926); 3, right periotic (USNM 22953); 4,
right periotic (USNM 11234). 5-8, External views: 5, left periotic (USNM 22952); 6, left periotic (USNM 22926); 7, right peri-
otic (USNM 11234); 8, right periotic (USNM 22953).
ce
UNITED STATES NATIONAL MUSEUM BULLETIN 247
FOSSIL MARINE MAMMALS
From the Miocene Calvert Formation
of Maryland and Virginia
Parts 3 and 4
REMINGTON KELLOGG
Research Associate, Smithsonian Institution
MUSEUM OF NPA URAL ES i OrRay.
SMITHSONIAN INSTITUTION +¢« WASHINGTON, D.C. « 1966
For sale by the Superintendent of Documents U.S. Government Printing Office Washington, D.C. 20402-Price 75 cents
3. New Species of Extinct Miocene Sirenia
4, A New Odontocete From the Calvert
Miocene of Maryland
3. New Species of Extinct Miocene Sirenia
IRENIANS ARE CURRENTLY REGARDED as having an early
S Eocene, possibly Paleocene, derivation from a land
mammal stock which gave rise also to the Proboscidea and
Desmostylia. In the course of geological time their descend-
ants have evolved as two readily distinguishable families,
the dugongs (Dugongidae) and the manatees (Trichechidae).
Within historical times dugongs have been inhabitants of
the Indian Ocean from Mozambique and Madagascar,
north to Kenya and the Red Sea, the Malabar coast of
southwest India, Ceylon, Andaman Islands and Mergui
Archipelago in Bay of Bengal, North Pacific Ocean from
Taiwan south to Philippine Islands, Malaysia and northern
Australia. A markedly bent-downward rostrum and re-
duced dentition characterized, in part, the dugongs as early
as the Miocene.
Manatees are restricted in the Recent fauna to the coast
and coastal waters of the United States from Beaufort, N.C.,
to the Florida Keys, coasts of Gulf of Mexico, Carib-
bean coasts of Central America, coasts and lower reaches of
rivers of northeastern South America, and the West Indies;
occurring also in west African coastal waters and the larger
rivers from Senegal to Angola. Reduplicated bilophid
cheek teeth and a slightly deflected rostrum are readily
recognizable characteristics.
Recorded antecedent geological history of the Sirenia
commences with Protosiren and Eotheroides (middle Eocene
of Egypt) and Prorastomus (Eocene of Jamaica). Later
stages of development of structural modification of du-
gongids occur in the Oligocene of Germany, Belgium, and
France; in the Miocene of Austria, Switzerland, Belgium,
France, and Italy; and in the Pliocene of France and Italy.
True dugongids were also present in the marine faunas of
the western North Atlantic at least as early as the Oligocene
and as late as the Pliocene.
_ Knowledge of the early geological history and geographic
distribution of the Sirenia in the western hemisphere is
limited to sporadic occurrences of somewhat divergent and
apparently not closely related types. From the supposedly
deep water lower Eocene (Manasquan formation) marl
pits along Shark River, Monmouth Co., N.J., Cope (1869,
pp. 190-191, pl. 5, fig. 6) described a portion of a tooth,
which resembled the incisor tusk of a dugong, as Hemicaulo-
don effodiens. The identity and relationship of this tooth
fragment will be dealt with in the description of the
dentition of the Calvert sirenian.
Owen (1855, p. 543) bestowed the name Prorastomus
strenoides on the skull and mandibles of a primitive sirenian.
This specimen was found embedded in a hard gray lime-
stone nodule (Owen, 1875, p. 559) in the river bed on
Freeman’s Hall estate between the parishes of St. Elizabeth
and Trelawney, Jamaica, possibly from the Richmond beds,
lower Eocene. The type skull of Prorastomus sirenoides
(BMNH 44897, Dept. Geology), measures 269 mm. from
the incomplete posterior face of the occipital condyle to the
worn anterior end of the premaxillary, and the estimated
width across the postorbital angles of the supraorbital
processes of the frontals is 86 mm. The length of the right
mandible from the angle to the anterior end is 230 mm.
and the length of the symphysis, 73.5 mm. On this par-
tially prepared type specimen nine teeth are visible in the
right mandible; in the right maxillary, six teeth occupy an
interval of 69-++ mm. The upper incisors are not enlarged
as tusks. The molar teeth appear to be low crowned with
cusps forming two transverse crests. The elongated pre-
maxillaries enclose a short mesorostral fossa (50-+ mm.).
The rostrum is narrow, measuring 45 mm. at the level of
the anterior end of the mesorostral fossa. The mandibular
symphysis is strongly compressed anteriorly (width, 21.5
mm.). No noticeable bending downward of the symphysial
end of the mandibles is observable. An incomplete humer-
us from the island of Sombrero, Lesser Antilles, was later
referred to the same species by Lydekker (1887). More
recent geological studies assign a Miocene age to the
sediments on this island.
From Tertiary calcareous shales in a bluff on the west
bank of the Jacagnas River, 1 km. north and | km. west of
Juana Diaz, Puerto Rico, Matthew (1916) described as
65
66 UNITED STATES NATIONAL MUSEUM BULLETIN 247
?Halitherium antillense a \eft mandible lacking the symphysis
and the teeth anterior to the three molars. Middle Oligo-
cene age is now attributed to these Juana Diaz shales.
Another middle Oligocene Puerto Rican dugongid, Caribo-
siren turnert, but apparently younger in gelological age, con-
sisting of the skull, four dorsal vertebrae and ribs from the
San Sebastian shales exposed on a hillside between Sebastian
and Lares, has been described by Reinhart (1959, p. 8).
The skull of this dugongid lacks incisors, M® is without
posterior cingulum or hypoconule, rostrum is strongly bent
downward anteriorly, and nasals are separated on midline
by the frontals. A small sirenian, whose vertebrae and ribs
exhibit some resemblance to the middle Oligocene (Stamp-
ian) Halitherium schinzi of Germany, has been recovered
from the upper Oligocene Chichasawhay marl and lime-
stone in Wayne County, Miss., and Clarke County, Ala.
Another dugongid represented by a considerable portion
of the skeleton was excavated in a fuller’s earth mine in
Gadsden County, Fla. Simpson (1932a, p. 426) named this
middle Miocene (Hawthorn formation) sirenian Hespero-
siren crataegensis. ‘The skull is characterized in part by the
absence of incisors, slightly deflected rostrum, nasals separ-
PART 3
ated in midline by frontals, and supraoccipital nearly or
just meeting the foramen magnum.
At least one member of the family Dugongidae, Felsino-
therium ossivallense (Simpson, 1932a, p. 448), persisted until
the middle Pliocene on the Florida coast. Cranial and
other skeletal elements were recovered in dredging the Bone
Valley formation at Mulberry, Polk Co., Fla.
The oldest sirenian definitely identified as a trichechid
thus far recorded is Potamosiren magdalensis (Reinhart, 1951)
from the late Miocene La Venta fauna in Huila Dépt.,
Colombia. The left mandible and the posterior lower
molar confirm this family allocation. This Miocene
sirenian, however, may not be a direct ancestor of the
living Trichechus.
Occurrences of indeterminate ribs and teeth of trichechids
from Pleistocene deposits of North and South America
have been reported in the literature. It would appear
that the family Trichechidae had a long developmental
history, the details of which remain largely obscure.
No reference to the Cenozoic developmental history of
the Sirenia on the Pacific coast of North America was
contemplated when this study was undertaken. Additional
comments on some of the Cenozoic sirenians of the northern
hemisphere will be made in the following text.
THE CALVERT MIOCENE DUGONG
The first recorded occurrence of sirenian vertebrae and
a rib on the western shore of Maryland, although erroneous,
was published by Harlan (1825, p. 236). Presumably these
bones, at that time, had been deposited in the collections of
the Academy of Natural Sciences of Philadelphia (ANSP);
but, if such was the case, they have not since been recognized.
The vertical diameter of the atlas of this supposedly gigantic
species of fossil Manatus measured nine inches and its trans-
verse diameter eleven inches. The measurements of the
atlas indicate a species of mysticete, but as no locality was
given there is no certainty that the bones were derived
from a Miocene formation or even fossilized. Seventeen
years later, DeKay (1842, p. 123) named these remains
M[anatus] giganteus.
When preparing the mammalian text for the systematic
paleontology of the Miocene deposits of Maryland, Case
(1904, p. 56, pl. 26, fig. 1) referred an ankylosed radius
and ulna from the Calvert formation at Fairhaven, Md.,
“evidently a small species,” to (?) Trichechus giganteus. No
further mention of fossil Sirenia appeared in the literature
until Palmer (1917, p. 334) recorded the finding of the
neural arch and spine of a fifth dorsal vertebra which he
regarded as related to the extinct Steller’s sea cow (H)dro-
damalis stellert). This vertebra is now referred to the Calvert
sirenian herein described.
The first Calvert sirenian specimen was received for the
national collections in 1905, and since then more adequate
materials were added in 1936, 1939, and 1943. Portions
of several individuals of this Miocene dugong have been
recovered from the exposures of the Calvert formation on
the western shore of Chesapeake Bay. Young, immature,
and old adult individuals are represented by teeth and
other skeletal parts, but articulated or otherwise complete
skeletons have not been found. In many instances the
bones are scattered in the stratum in which they were found.
The occurrence in this formation of plant eating sirenians
belonging to age classes from quite young to old adults
suggests the existence of luxuriant growths of sea-water
algae and succulent aquatic plants.
Dall in 1904 interpreted the Maryland Calvert molluscan
assemblage to indicate shallow marine waters and somewhat
warmer temperatures than at present in the Chesapeake
Bay region. Analysis of the Calvert plants collected at
Richmond, Va., led Berry in 1917 to conclude that the
coastal region was low bordered by bald cypress ( Taxodium)
swamps.
NEW SPECIES OF EXTINCT MIOCENE SIRENIA 67
Marine, fresh water and terrestrial inhabiting vertebrates
comprise the Calvert fauna, indicating that one or more
rivers discharged fresh water into a large estuary. Drowned
land vertebrates may have been carried down stream in a
river, especially during heavy precipitation resulting in the
flooding of lowlands adjacent thereto. Animals of this
kind may have been trapped wherever high banks pre-
vented escape when the shore was flooded by high tides.
The larger mammals may have been mired in the mud
and sandy silt of tidal marshes and swamps. The occur-
rence in these deposits of land mammals, including the
mastodont (Gomphotherium), the tapir (Tapiravus), rhinoc-
eros (Aphelops), horses (Archaeohippus and Merychippus),
peccaries (Cynorca and Hesperhys), and the dog (Tomarctus)
may be attributed to some such fate. In most instances
these occurrences are limited to teeth or isolated bones.
The former presence of a hair seal (Leptophoca) is revealed
usually by a single limb bone and more rarely by a ver-
tebra. Innominate bones of three individuals have been
added to the national collections.
When a marine mammal was washed ashore either dead
or dying, its flesh and viscera would soon be removed by
scavengers, leaving the at least partially disarticulated
skeleton to be scattered by rising and ebbing tides, storm-
driven waves, and washouts resulting from heavy rains.
Articulated skeletons would seldom be preserved unless
the carcass was tossed above the breaker zone and buried
in the sand. Skeletons of some of the stranded carcasses
on sand bars may also have been scattered by tidal surf,
while the disassociation of those that sank in deeper water
at death may have been affected by tidal scour (Kellogg
and Whitmore, 1957, p. 1022).
With two exceptions all of the whalebone or mysticete
specimens excavated have been young or immature indi-
viduals. Considerable portions of the skeletons of adult
porpoises have been discovered, including the long-beaked
Karhachis and Eurhinodelphis and the short-beaked Delphinodon
and Kentriodon. Skeletal elements, particularly vertebrae
and ribs, have been found in normal sequence of relation-
ship, relatively undisturbed and presumably were quickly
covered with sediments after death. The majority of the
odontocete remains found, however, have the epiphyses
detached from the centra and are thus either young or
immature individuals.
Crocodile (Thecachampsa) teeth are of fairly frequent
occurrence and these reptiles were sufficiently numerous to
play an important predatory role. Teeth of this Miocene
crocodile like those of its notably aggressive Recent relative
are not adapted for chewing. Although the crocodile can
eat anything that can be swallowed whole, if the victim
is too large the crocodile tows it away with its clamplike
jaws to a hoarding spot where it will decay and become
soft enough to be readily torn apart. Flesh and bones
when swallowed are rapidly digested and no telltale rem-
nants would survive to puzzle some future fossil hunter.
The rather frequent intercalation of layers of sand in the
Calvert formation should have provided suitable nesting
habitats for the Miocene crocodile. Recent crocodiles lay
their eggs in holes or depressions in sun-warmed sand
where they remain covered until they hatch.
Many bones reveal clearly the gashes or scratches made
by the teeth of sharks. Shark’s teeth have been noted em-
bedded in badly scarred vertebrae, limb bones, and man-
dibles. The presence of such a preponderance of immature
or young marine mammals suggests that this region was
the calving grounds for the mysticetes, the sperm whales
and probably some of the smaller odontocetes. The appar-
ent abundance of readily obtainable prey undoubtedly
attracted the sharks. Teeth of sharks have been so plentiful
along the beach in the tidal wash that many a young boy
has filled a quart jar during the short stay at one of the
Chesapeake summer vacation residences. Since their rep-
resentatives in the Recent oceanic faunas are recognized
voracious predators, it can be assumed that their Miocene
forebears had similar habits. Among the kinds thus far
identified are the cow shark (Hexanchus), the mackerel or
mako shark (Isurus), the tiger shark (Galeocerdo), the requiem
shark (Hemipristis), the gray shark (Carcharhinus), and the
white shark (Carcharodon). The shark-toothed porpoise
(Squalodon) undoubtedly was a predator.
Isolated or a few consecutive vertebrae of large fishes of
the mackerel tribe or scombroids such as the tuna and bill
fishes as well as other smaller bony fishes show they were
also the victims of predators.
Of the fossil turtles thus far recognized in the Calvert
fauna, the Miocene leatherback turtle (Psephophorus) and
the green turtle (Chelonia) are undoubtedly pelagic types,
the soft shell turtle (Amyda) and the side necked turtle
(Taphrosphys) are fresh water, probably river, and the
tortoise (Testudo) terrestrial.
Unless the way of life of the vertebrates comprising the
Calvert fauna was materially altered in the course of sub-
sequent geological time, typical pelagic seasonal migratory
types such as the whalebone whales (Mysticeti), some of
which resort to bays and lagoons at calving time, were
associated with the marine green turtles and leatherbacks
that deposit their clutch of eggs before the hatching season
on sandy beaches, the clannish hair seals that congregate
ashore or on offshore islands, and the dugongs and croco-
diles that inhabit shallow bays as well as brackish and
fresh water swamps.
It seems advisable to review the status of three genera
that have been proposed for fossil dugongs that exhibit
some rather close structural resemblances to the Calvert
sirenian.
68 UNITED STATES NATIONAL MUSEUM BULLETIN 247
FELSINOTHERIUM Capellini
Felsinotherium Capellini, 1865, Atti Soc. Ital. Sci. Nat. Milano,
vol. 8, p. 281. [Nomen nudum; no descriptive term except
“rosso mammifero fossile.””] Type species not named except
for statement ‘“‘dedica al Signor Foresti’’.
Felsinotherium Capellini, 1871, Mem. Accad. Sci. Inst. Bologna,
ser. 3, vol. 1, p. 616.
Type Species: Felsinotherium forestii Capellini.
Type Locality: ‘‘Molassa giallastra,” Riosto, Bologna,
Italy. Astian, middle Pliocene.
The lower Pliocene (Plaisancian) Felsinotherium serresii has
simple and primitive bunodont molars. These cheek teeth
have six cusps in two rows modified by slightly more for-
ward placement of the median posterior cusp (metaconule).
Accessory cuspules are developed on the anterior and
posterior cingulum. The length of the skull varies from
370 to 420 mm.
The middle Pliocene (Astian) Felsinotherium forestii is
characterized by relatively high-crowned cheek teeth
(Capellini, 1872, pl. 4), which are rather complex, in part
resulting from the crowding of the cusps, which tends to
mask the original two row arrangement pattern and the
partial blocking or reduction of the transverse valley. The
skull is large, length 540 to 620 mm., and massive; the
rostrum is broadened, possibly more abruptly deflected
than serresit, supraorbital processes of frontals are shorter
and broader, and mesorostral fossa is elongate and narrow.
Minor and seemingly unimportant differences have been
proposed to separate the genera Metaxytherium and Felsino-
therium. Abel (1904, p. 217) contended that Felsinothertum,
chiefly with reference to F. forestii and Cheirotherium brocchii
(Cheirotherium Bruno, 1839, preoccupied by Chetrotherium
Kaup, 1835, a genus of reptiles) was a more highly spe-
cialized type, as shown by the following characteristics:
body size, form of skull roof and separation of temporal
crests, relation of supraoccipital to foramen magnum, re-
duction stage of nasals, bending of jaw, development of
tusks in premaxillaries, number of molars, form of molars,
form of scapula, and geological age.
Depéret and Roman (1920, p. 48) distinguish Felsino-
therium from Metaxytherium by the little more advanced re-
duction and the little more quadrate form of M!, M7?,
and Pm‘, and by the little more pronounced bending
downward of the premaxillary of the rostrum. Comparison
of the profiles of Metaxytherium cuvierii (Cottreau, 1928, pl. 1,
fig. 2c) and Felsinotherium serresti (Depéret and Roman,
1920, pls. 1, 2, fig. la) does not confirm this mentioned
difference in the bending downward of the rostrum.
Simpson (1932a, pp. 451, 469) in describing Felsino-
therium ossivallense from the lower Pliocene Bone Valley
formation at Mulberry, Fla., defends this generic allocation
on the basis that the upper molariform teeth are wider
PART 3
relative to their lengths in Feélsinotherium than in Metaxy-
therium, although no constant morphological differences
were noted in isolated molars. He regarded Felsinotherium
more progressive, but commented (op. cit., p. 469) “at
present no single character can be relied on to separate all
the species of this genus from all the species of Metaxy-
therium.”” Photographs were published by Simpson (1932a,
fig. 12) of the rostral portion of a skull which was mis-
placed at the time of his study; its subsequent location
has provided supplementary information. As regards the
lengthening of the proximal portion of this rostrum, Gregory
(1941, p. 39) observes that Felsinotherium ossivallense corres-
ponds more closely with Metaxytherium cuviertti than with
European species of Felsinotherium and stresses the doubtful
value of the length-width ratio of M°, inasmuch as the 1.24
ratio of this referred specimen agrees more closely with
species of Metaxythertum than with Felsinotherium. These
observations undoubtedly influenced Gregory to regard
“the differences between Miocene and Pliocene Halithe-
rinae as too slight and variable to be worthy of generic
recognition,”’ but he nevertheless concluded that until more
adequate material was available a formal proposal would
be premature.
The validity of the suggested diagnostic distinctions
between Metaxytherium and Felsinotherium are far from being
convincing. It would appear advisable, however, to defer
further consideration of the status of these genera until
additional species that exhibit some fairly close relationship
to presently recognized forms are discovered.
HALIANASSA Studer
Halianassa Meyer, 1838, Jahrbuch fiir Mineralogie, Stuttgart, p.
667. [nomen nudum.] Type species: Manatus studeri Meyer
(nomen nudum).
Halianassa Studer, 1887, Abhandlungen Schweizerischen palaonto-
gischen Gesellschaft, Zurich, vol. 14, p. 10.
Type Species: Halianassa studeri Studer.
Type Locality: Muschelsandstein von Maggenwyl bei
Lensburg, Aargau Canton, Switzerland. Burdigalian,
lower Miocene.
Manatus studeri was proposed by H. von Meyer (1837, p.
677), without description, for a portion of the left maxillary
with four cheek teeth from the Burdigalian ‘Molassen-
Sandstein” at Maggenwyl, Switzerland. The name is
unquestionably a nomen nudum. The following year,
Kaup (1838, p. 319, pl. 2, figs. D1, D2) described briefly
and illustrated a lower molar [=Halitherium schinzi, fide
Lepsius, 1882, p. 161] from Flonheim, Rhineland-Palatinat,
Germany, that measured 21 mm. in length and 17 mm. in
width. This tooth was considered to belong to Hippopota-
mus dubius of Cuvier [=?Protosiren dubia, fide Sickenberg,
NEW SPECIES OF EXTINCT MIOCENE SIRENIA 69
1934, p. 190] whose corresponding tooth measured 18 mm.
in length and 14 mm. in width. The measurements of the
same tooth of the middle Miocene (Helvetian) Hippopotamus
medius of Cuvier were recorded as 28 mm. in length and
width. This Flonheim molar has since been allocated to
the Oligocene Halitherium schinzi Kaup.
In the same volume H. von Meyer (1838, p. 667) proposed
the generic name Halianassa for the “‘widespread plant-
eating’’ fossil of Flonheim (Kaup, 1838, p. 319), which
was regarded as standing between Halicore dugong and
Manatus. The sirenian tooth from Flonheim was identified
by Kaup as the Hippopotamus dubius of Cuvier (ed. 2, 1824,
vol. 5, pt. 2, p. 527 =?Protosiren dubia, fide Sickenberg,
1934, p. 190) from Blaye, Gironde, France. The Hippo-
potamus medius of Cuvier (ed. 2, 1821, vol. 1, p. 332, pl. 7,
fig. 9) had been so named by Desmarest (1822, p. 388).
To the same animal H. von Meyer (1838) referred the
stone block with the Raedersdorf skeleton in the Strasburg
Museum (Duvernoy, 1835a-b; Blainville, 1844, pp. 100-
102, pl. 10, also refers to this specimen). H. von Meyer
(1838) also stated that he did not doubt that Halicore cuviert
Christol, then also Cuvier’s “Hippopotamus medius and H.
dubius’, as well as his Manatus studert (a nomen nudum)
belong thereto, which he then named Halianassa studert,
but again without a description. The portion of the left
maxillary with four cheek teeth in place as well as the four
root cavities of two missing anterior teeth from the Bur-
digalian sandstone at Maggenwyl was neither described
nor illustrated as the type of Halianassa studeri until 1887
(Studer, p. 10, pl. 1, fig. 4).
In 1843, Hermann von Meyer (p. 704) concluded that
the sirenian mandibles excavated in the Aquitanian sand
near Linz, Austria, and described as Halitherium cristolu by
Fitzinger (1842, p. 61) belonged to the genus Halianassa
which he (Meyer, 1838, p. 667) had proposed for the
Flonheim sirenian and for which Halitherium schinzi Kaup
is now recognized as the valid name. Four years later,
in 1847, Hermann von Meyer (p. 189) employed the name
Haltanassa collinit for unlisted sirenian bones in the custody
of Carl Ehrlich at the Linz Museum but published no
description of them. Ehrlich (1848, p. 200) accepted the
identification given by H. von Meyer and applied the name
Halanassa collin to the sirenian mandibles described by
Fitzinger in 1842 as Halitherium cristolii as well as to a left
scapula and two fragments of cranial roofs. This left
scapula as well as ribs and vertebrae recovered in 1854 at
Linz were also described as Halianassa collinii by Ehrlich
(1855, pp. 11-21, figs. 5). All of these skeletal elements
referred to Halianassa collinit are considered by Spillmann
(1959, p. 17) to be identical specifically with the sirenian
mandibles found in the Sicherbauer-Sandgestatten at
210-301—66——2
Linz which Fitzinger (1842, p. 61) named Halitherium
cristolit.
Thus, the generic name Halianassa is not available as a
replacement for Metaxytherium under either of the above
stated usages.
Depéret and Roman (1920, p. 33) while commenting on
the inadequacy of our knowledge of Halianassa studert
suggest that this species is perhaps identical with Metaxy-
thertum beaumonti (whose skull has been reported to be lost)
and M. krahuletzi. The generic attributes of the species
currently assigned to either Halianassa or Metaxytherium are
so doubtful in the opinion of Simpson (1932a, p. 475) that
he suggested the retention tentatively of both genera.
Reinhart (1959, p. 23) in his excellent review of the Sirenia
of the western hemisphere has employed the generic term
Halianassa. This usage has been accepted by others.
Nevertheless, should Metaxytherium Christol prove to be
synonymous with Halianassa Studer, the former has at
least 46 years priority and is valid. Whether or not the
subquadrate upper molars of Halianassa studeri are suffi-
ciently diagnostic to warrant generic recognition should
await discovery of more adequate skeletal material.
The measurements (in mm.) of the cheek teeth of the
type of H. studert published by Studer (1887, pp. 11-12,
pl. 1, fig. 4) are
length width
Pm? 17 18.5
M! 20 23
M2 22 22
M3 31 25
and on the basis of the illustration (pl. 43, fig. 3), the cheek
teeth are characterized as follows:
M!: narrow transverse lake between rim of anterior
cingulum and the continuous rim encircling the protocone,
protoconule, and paracone; transverse valley deflected by
forward thrust of metaconule; continuous rim encircles met-
aconule, hypocone and posterior cingular lake; metacone
conical, apex behind metaconule.
M?: anterior cingulum wide, rolled over backward;
anterior lake narrow, transverse; protocone, protoconule,
and paracone almost in straight transverse row; transverse
valley narrow, curved forward medially; hypocone prom-
inent, continuous with metaconule and separated from
smaller conical metacone by narrow curved cleft; apex of
metacone behind metaconule; posterior cingulum mi-
nutely cuspidate.
M®: apices of protocone, protoconule and paracone in
straight transverse row; incipient parastyle on thick crest
of anterior cingulum separated from paracone by a deep
cleft; anterior transverse lake narrow, deep; transverse
valley curved, similar to that of M?.
70 UNITED STATES NATIONAL MUSEUM BULLETIN 247
METAXYTHERIUM Christol
Metaxytherium Christol, 1840, Compt. Rend. Acad. Sci., Paris,
vol. 11, no. 12, p. 529; L’Institut, Paris, vol. 8, sect. 1, no. 352,
p. 323, September 24, 1840; Ann. Sci. Nat., Paris, ser. 2,
vol. 15, pp. 331-335, pl. 7, figs. 1-3, 5-6, 9-10, June 1841.
Type Species: Not mentioned. By restriction, Metaxy-
therium medium (Desmarest).
Type Locality: ‘‘Falun,” vicinity of Doué, Maine-et-
Loire, France. Helvetian, middle Miocene.
This genus was based on specimens from the departments
of Maine-et-Loire, Gironde, and Herault, France. The
specimens specifically mentioned by Christol were: (1)
the top of the braincase (Cuvier, 1825, ed. 3, vol. 5, p. 267,
pl. 19, figs. 22, 23) from the marine Miocene (Helvetian),
vicinity of Doué, Maine-et-Loire, referred by Cuvier to
the “amantin” (sea cow); (2) the isolated upper molar
teeth (Cuvier, 1825, ed. 3, vol. 1, pp.333-334, pl. 7, figs.
12-17, 18-20; referred subsequently to Halithertum dubium
by Gervais, 1859, p. 282 [=?Protosiren dubia, fide Sicken-
berg, 1934, p. 190]) from the Eocene (Lutetian) “‘calcaire”
near Blaye, Gironde, France, referred by Cuvier (1824)
to Hippopotamus dubius; (3) the three lower molars in the
left mandible (Cuvier, 1825, ed. 3, vol. 1, p. 332, pl. 7,
figs. 9, 10, 11) from Doué referred by Cuvier to the “moyen
hippopotame fossile’ [=Hippopotamus medius Desmarest,
1822]; (4) The proximal and distal ends of the left humerus
(Cuvier, 1825, ed. 3, vol. 5, p. 233, pl. 19, figs. 24-26, 28,
29; illustrations reversed by engraver, fide Christol, 1841,
p. 328, footnote) from Doué referred by Cuvier to “deux
phoques”’ (seals); (5) right radius and ulna (Cuvier, 1825,
ed. 3, vol. 5, p. 268, pl. 19, figs. 19-21; illustrations re-
versed by engraver, fide Christol, 1841, p. 328, footnote)
from Doué referred by Cuvier to the “‘lamantin’” (sea
cow); and (6) perhaps the rib and the vertebra (atlas)
(Cuvier, 1825, ed. 3, vol. 5, p. 269, pl. 19, fig. 12A, 12B)
from Doué referred by Cuvier at first to the “lamantin”’
and afterwards to the “morse”? (walrus).
The specimens discovered in the Pliocene (Plaisancian)
at Montpellier, Herault, included (1) most of the right
mandible (except for the portion comprising the coronoid
process and the condyle) with three molars in place and
ankylosed at the symphysis with the anterior portion of the
left mandible; (2) the skull; (3) the molars; (4) many ribs;
and (5) many vertebrae.
The type species was not specifically fixed in the original
description. Christol (1840, p. 529), however, recognized
that his genus comprised two different species differing
principally in size, the larger sirenian occurring in the
Miocene of Maine-et-Loire and the smaller in the Pliocene
of Montpellier.
Christol, however, in 1834 (p. 274 and p. 277 explanation
for pl. 13) had referred the sirenian from Montpellier and
PART 3
the one from Doué to Halicore cuvierti nobis. Some years
later, Christo] (Blainville, 1844, p. 130) in a letter to Blain-
ville concluded that his genus Metaxytherium comprised the
following three species: Metaxytherium cordieri for the Loire
Valley sirenian, Metaxytherium cuvieri for the Montpellier
sirenian, and Metaxytherium beaumonti for the ‘‘molasse de
Beaucaire” sirenian. The smaller Montpellier sirenian
subsequently also became the type of Halitherium serresii,
but Gervais (1849, vol. 2, expl. pls. 4, 5; 1849, vol. 1, pt. 1,
p. 219; 1850, vol. 1, pt. 2, p. 406; 1859, p. 277, pl. 4, figs.
1-3, pl. 5, figs. 1-3, pl. 6, figs. 1-5) did not accept Metaxy-
thertum as a valid genus in his review of European fossil
sirenians.
The status of the Doué and the Montpellier sirenians
remained in question for several years. Capellini in 1865
(p. 281) proposed Felsinotherium for an Italian Pliocene
(Astian) sirenian, but did not formally name the species
Felsinotherium forestit until 1871 (p. 617, pls. 1-8). Capellini
(1871, p. 615), however, seems to have been the first to
place Halitherium serresit Gervais among the species included
in the genus Felsinotherium, but did not actually publish
the combination. Zigno (1878, p. 944) discussed the Mont-
pellier sirenian under the name Felsinotherium serresii. This
removal of the Montpellier serrestz to Felsinotherium restricted
the application of Metaxytherium and also of Halicore cuvierit
to the Maine-et-Loire specimens listed by Christol. The
type species of Metaxytherium by this removal becomes
Halicore cuvierii Christol (1834, p. 274 and p. 277, explanation
for plate 13), which is antedated by Hippopotamus medius
Desmarest (1822), based on the left mandible (MNHN 722,
Laboratoire de Paléontologie) with three molars in place,
but M, lacks the crown (Cuvier, 1821, ed. 2, vol. 1, p. 332,
pl. 7, fig. 9; illustration reversed by engraver), and one
isolated molar from Doué. The measurements of the molar
teeth in the type mandible illustrated by Blainville (1844,
pl. 9) are as follows: Mo, length, 26 mm., and width,
21.7 mm.; M3, length, 28.7 mm., and width, 24 mm.
The type species of Metaxytherium now stands as Metaxy-
therium medium (Desmarest).
Diagnosis: Incisors (tusks) present in premaxillaries of
adult males; cheek teeth with enamel; upper cheek teeth
reduced to three molars and one premolar (in young at
least); one premolar and three molars comprise lower
dentition; M* unreduced, complex, elongate with accessory
cuspules; conules displaced, bunodont (unworn); roots of
cheek teeth at least partially closed.
Skull: Braincase relatively long, high, and narrow; ros-
trum deflected downward to some degree; nasal bones sep-
arated at posterior end of mesorostral fossa on midline by
the paired frontals; lachrymal present; no lachrymal duct;
supraorbital processes of frontals relatively long, slender
and little expanded; temporal crests lyriform, either well
separated or closely approximated on parietals; median
NEW SPECIES OF EXTINCT MIOCENE SIREINIA 71
area of paired frontals flattened; supraoccipital narrowly
reaching downward to foramen magnum; external palatal
projection of maxillary suturally united with jugal as in
Dugong; skull as long as 600 mm. Mandible deep and
robust.
Anterior dorsal vertebrae with three pairs of facets for
articulation with ribs, one at end of the diapophysis and
the anterior and posterior demifacets on each centrum of the
first nine dorsals; nineteen to twenty dorsal vertebrae,
three lumbar vertebrae, one sacral vertebra, and possibly
twenty or more caudal vertebrae; nineteen to twenty pairs
of ribs; three processes present on vertebral end of first
rib, two of which bear the articular surfaces of the capitulum
and the tuberculum.
Radius and ulna of adults firmly ankylosed, rotation
completely lost; radius bent forward, ulna inward; innomi-
nate bone reduced to elongated slender ilium, laterally
compressed ischium, and pubis vestigial if retained; artic-
ular socket for head of femur shallow and small.
The diagnostic differences observable in the skull, scap-
ula, and the maxillary and mandibular molars of the genera
Halitherium and Metaxythertum have been tabulated by
Spillmann (1959, p. 54).
METAXYTHERIUM CALVERTENSE, new species
Type Specimen: USNM 16757. Immature sirenian.
Skull (lacking on left side: the maxillary, the entire series
of cheek teeth, the jugal; also both palatines, right occipital
condyle, and descending processes on each side of the pte-
rygoid, and the coalesced alisphenoid and basisphenoid);
right mandible and symphysial portion of left; both scap-
ulae; both humeri; distal portion of left radius; axis and 3
cervical vertebrae; 16 dorsal vertebrae; neural arch and
spine of 3 lumbar and 1 sacral vertebrae; 3 transverse pro-
cesses of lumbar vertebrae; 40 ribs; sternum; right innomi-
nate. Collectors, W. E. Salter, A. C. Murray, and C. W.
Gilmore; August 4, 1943.
Horizon and Locality: One-half mile south of Plum Point
Road end, Calvert Co., Md. In compact blue clay at base
of zone 11 (below shell band) and at tide level at base of
cliff. Calvert formation, middle Miocene.
Referred Specimens: Ten, as follows: (1) USNM 9346:
adult sirenian, left radius and ulna (figured by Case, 1904,
pl. 26, fig. 1); Fairhaven, Anne Arundel Co., Md., diato-
maceous earth, Calvert formation, middle Miocene. (2)
USNM 12596: adult sirenian, 2 dorsal vertebrae, 8 more
or less complete ribs and fragments of others; coll. Norman
H. Boss and Remington Kellogg, June 19, 1932; at begin-
ning of cliff south of Plum Point wharf, Calvert Co., Md.,
in zone 12 at contact between zone 12 and 11, 4 feet above
shell band (zone 10), Calvert formation, middle Miocene.
(3) USNM 16630: young sirenian, both mandibles, anky-
losed anteriorly (4 cheek teeth in situ and 2 detached milk
teeth), left occipital condyle, axis, 7 dorsal, 3 lumbar, 1
sacral, and 2 caudal vertebrae, 12 ribs, right scapula; coll.
G. E. Marsh, Dec. 24, 1939; 646 yards south of mouth of
Parker Creek, Calvert Co., Md., in bluish sandy clay, zone
12, Calvert formation, middle Miocene. (4) USNM 16715:
young sirenian, left scapula; coll. William E. Salter, July
11, 1942; 1,400 feet south of mouth of Parker Creek (in
second cliff), Calvert Co., Md., in blue clay of zone 11,
about 3 feet below top of zone, Calvert formation, middle
Miocene. (5) USNM 23213: adult sirenian, 8 dorsal and
2 lumbar vertebrae, portions of 2 scapulae, 2 incomplete
ulnae, 1 incomplete left radius, left innominate, 2 rather
complete ribs and portions of about 12 others; coll. R. Lee
Collins, May 8, 1936; about 0.6 mile south of Randle Cliff
Beach, Calvert Co., Md., in talus slope at foot of cliff (little
doubt but that specimen came from zone 10), Calvert
formation, middle Miocene. (6) USNM 23271: adult si-
renian, second molar of left mandible; coll. A. Shaftsbury,
Sept. 11, 1933; 1 mile south of Plum Point wharf, Calvert
Co., Md., in lower part of zone 11 at shell layer, Calvert
formation, middle Miocene. (7) USNM 23281: adult si-
renian, third molar of right maxillary, worn; coll. T. E.
Ruhoff, May 30, 1956; midway between Plum Point and
Dare’s wharf, Calvert Co., Md., in shell layer of zone 11
at base of cliff on farm of Mr. Andrews, Calvert formation,
middle Miocene. (8) USNM 23348: adult sirenian, neural
arch and spine of fifth dorsal vertebra (see Palmer, 1917,
p. 234); coll. William Palmer, March 1916; 1 mile south
of Chesapeake Beach, Calvert Co., Md., Calvert formation,
middle Miocene. (9) USNM 23667: adult sirenian, axis;
coll. R. Lee Collins, Apr. 7, 1934; about 1 mile south of
Plum Point wharf, Calvert Co., Md., at shell layer at base
of zone 11, Calvert formation, middle Miocene. (10)
USNM 23409: adult sirenian, right third upper molar;
coll. R. Lee Collins; Calvert Cliffs, Calvert Co., Md. (no
other data), Calvert formation, middle Miocene.
Skull
This description is based on the skull (USNM 16757) of
an immature individual, the sutural contact between the
squamosal and the parietal being open on both sides of the
braincase. On the left side the squamosal was displaced
when the skull was found, but has since been partially
corrected. On the left side, the maxillary, the anterior
portion of the zygomatic arch, the entire row of cheek
teeth, as well as the right occipital condyle are missing.
DorsaL virw.—The skull (fig. 32) is characterized in
part by elongation in conformity with the normal sirenian
construction, the top of the braincase being narrower than
the rostrum. The cerebral cavity as compared to that of
the Recent dugong is more elongated, somewhat com-
7(P UNITED STATES NATIONAL MUSEUM BULLETIN 247
pressed from side to side, truncated at both ends, and rather
flat dorsally.
The posterior or occipital face of the braincase is almost
vertical and the elongated premaxillaries are bent strongly
downward. The occipital condyles are not visible when
viewed from above. The ovoidal mesorostral fossa is also
noticeably elongated, widened near the middle of its length
and extends backward beyond the orbit.
The somewhat horizontal dorsal surface of the braincase
is slightly depressed longitudinally between the low flat-
FicurE 32.—Dorsal view of skull, USNM 16757, of Metaxytherium
calvertense, with left jugal restored and rostrum corrected for
distortion. Abbrs.: Fr., frontal; Ju., jugal; La., lachrymal;
m.f., mesorostral fossa; Na., nasal; Pa., parietal; Pmx., pre-
maxillary; s.or.pr., supraorbital process of frontal; Sq., squamosal
zyg., zygomatic process of squamosal.
PART 3
tened temporal crests. These crests strongly converge some
55 mm. anterior to the supraoccipital crest, where they are
separated by a minimum 15 mm. interval; they then grad-
ually diverge anteriorly until an interval of 50 mm. sepa-
rates them, and these crests become indistinct.
The elongated parietals are so intimately ankylosed to
the supraoccipital that no sutural contact is discernible.
At this contact posteriorly a low transverse crest is devel-
oped below which the occipital face abruptly descends to
the foramen magnum. Anteriorly the parietals make a
forklike sutural contact with the frontals. The narrowest
part of the braincase roof is about 95 mm. anterior to the
low transverse crest that marks the ankylosis of the supra-
occipital and the parietals; at this point the width is 65
mm. The roof widens slightly toward its anterior end
where its transverse width is about 75 mm. Inside the
temporal crests on the top of the braincase the maximum
length of the right parietal is 100 mm. and the maximum
length of the right frontal is 88 mm. The maximum width
of the intertemporal portion of the roof of the braincase is
about 75 mm. The shape of the sutural contact between
the parietals and the frontals is shown on plate 33.
In general configuration, the braincase (pl. 33, fig. 1)
agrees with those of other forms of Metaxytherium and
Felsinotherium. The anterior portion of the roof of the
braincase is contributed by the elongated frontals, and
the sutural contact between these bones medially is almost
obliterated, except anteriorly, by ankylosis along the mid-
line of the dorsal surface of the braincase. Anteriorly the
frontals contribute the posterior margin of the mesorostral
fossa and intervene between the opposite nasal bones.
Each frontal bone is prolonged laterally to form a rather
short and narrow, but bent downward supraorbital process
which overhangs the orbital cavity. ‘The maximum antero-
posterior diameter (38 mm.) of the extremity of the
right supraorbital process of the frontal does not exceed
ereatly the minimum diameter (35 mm.) of this process.
On each side above the olfactory chamber each frontal
from a dorsal view is overlain by a relatively narrow nasal
bone which in turn abuts anteriorly against the posterior
end of the premaxillary. Between these nasals the nar-
rowed anterior end of each frontal extends forward to the
nasal or mesorostral fossa, thus separating these bones
above the olfactory chamber.
The platelike nasal bones were found not fully preserved
when this fossil skull was prepared in the paleontological
laboratory. On each side of the posterior end of the meso-
rostral fossa, the narrow nasal bone was attached to or
lodged in the excavation on the inner border of the cor-
responding supraorbital process of the frontal, and abutted
anteriorly against the posterior end of the premaxillary.
The length of each nasal exceeded its width on the dorsal
surface of the skull.
NEW SPECIES OF EXTINCT MIOCENE SIRENIA 73
At the posterior end of the mesorostral fossa of Cari-
bostren, Hesperosiren, Metaxytherium, Thattatostren and Felsino-
therium, the nasal bones are separated by the forward pro-
jecting wedge of the frontals above the nasal chamber.
As a possible indication of some variability, it should be
noted that the nasals are almost in contact medially on one
skull of Felstnothertum serresii (Gervais, 1859, pl. 6, fig. 3).
This relationship of the nasals and frontals was employed by
Kretzoi (1941) to support his conception of phyletic rela-
tionship of genera. Kaltenmark asserts that on the cranium
from Chazé-Henry, a photograph of which was published
by Depéret and Roman (1920, pl. 7, fig. 3), the nasals
meet on the midline, but Reinhart (1959, p. 61) questions
this interpretation and believes that the right nasal is
labeled as the premaxillary (Kaltenmark, 1942, vol. 6,
p. 107, fig. 2).
As with all known sirenians, the slender premaxillaries
are well developed and contribute the external borders of
the mesorostral fossa. The left premaxillary is complete,
but the right premaxillary has at least 20 mm. of the extrem-
ity broken off. At the anterior end of the mesorostral fossa,
the premaxillaries are bent strongly downward and are
closely approximated, forming a symphysis of about 84 mm.
in length. No vestige of an alveolus even for a small incisor
tusk is present in the extremity of the left premaxillary,
but the internal surfaces of both premaxillaries are incom-
plete. This apparent absence of a tusk may indicate the
female sex. Although the extremity of the rostrum pro-
jected obliquely downward and forward, the extent of its
prolongation resembles Metaxytherium cuvierti (Cottreau,
1928, pl. 1, fig. 2c) more closely than Felsinotherium serresii
(Depéret and Roman, 1920, pl. 2, fig. la).
In front of the supraorbital process of the frontal the
external face of the premaxillary is in contact with the lach-
rymal. The lachrymal is also appressed against the antero-
dorsal end of the jugal.
The maxillary is not visible on the dorsal surface of the
skull. The relations and shapes of the bones enclosing the
mesorostral or nasal fossa correspond fairly closely with
Metaxytherium cuvierti (Cottreau, 1928, pl. 1, fig. 2). The
nasal passages enter this fossa from the rear and the pair
of orifices of the olfactory nerves open into the same area.
This mesorostral fossa is terminated anteriorly by the close
approximation of the premaxillaries, which meet in the
form of a symphysis to constitute the terminal portion of the
rostrum. On each side the premaxillary constitutes the
major portion of the downward directed rostrum which is
supported posteriorly and ventrally by the corresponding
maxillary. The sutural contact between each premaxillary
and the corresponding maxillary commences on each side
at the level of or near the posterior end of the incisive foram-
ina and terminates at or near the level of the supraorbital
process of the frontal.
Along the hinder portion of the mesorostral fossa, each
premaxillary is applied externally to the anterior face of
the supraorbital process of the frontal. At the posterior end
of the mesorostral fossa each premaxillary also abuts
against the anterior face of the corresponding nasal, thus
excluding the maxillary from any share in the dorsal bor-
der of the mesorostral fossa. Each nasal bone is mortised
into the internal face of the corresponding supraorbital
process of the frontal.
PosTERIOR VIEW.—Viewed from the rear, this skull (fig.
33) resembles somewhat closely that of Felsinotherium serresia
2 eas
Dr.pa.
FIGURE 33.—Posterior view of skull, USNM 16757, of Metaxythertum
calvertense, with right exoccipital and occipital condyle restored.
Abbrs.: c., occipital condyle; Ex.oc., exoccipital; f.m., foramen
magnum; Per., periotic; pr.pa., paroccipital process; p.t.,
posttympanic process of squamosal; S.oc., supraoccipital;
zyg., zygomatic process of squamosal.
(Depéret and Roman, 1920, fig. 2(4)), its greatest width
being above the level of the occipital condyles. The dorsal
border of the supraoccipital is truncated horizontally and
the rather sinuous curvature of the lateral lambdoid crest
is concave dorsally and convex ventrally. The contour of
the left occipital condyle is reniform, and the petrosal is
visible in the gap between the supraoccipital, the exoccipi-
tal and the ventral projection of the squamosal. The
foramen magnum is relatively large, higher than wide.
On this fossil skull, the exoccipital meets the thickened
supraoccipital in sutural contact almost at the level of the
top of the foramen magnum.
The posterior face of the braincase of Metaxytherium, new
species, from Chazé-Henry figured by Kaltenmark (1942,
vol. 6 p. 105, fig. 1) also has the supraoccipital extending
downward to the foramen magnum. The lateral gap in the
braincase wall between the squamosal, exoccipital and to a
limited extent the supraoccipital, which is filled by the
periotic, has a slightly different configuration either from
that of the Calvert sirenian or from the Recent dugong.
This gap is termed the supracondyloid fossa by Kaltenmark.
74 UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 8
Ficure 34.—Lateral view of skull, USNM 16757, of Metaxytherium calvertense, with rostrum corrected for distortion. Abbrs.: Al., descending
pterygoid plate of alisphenoid; Bo., basioccipital; c., occipital condyle; Fr., frontal; Ju., jugal; La., lachrymal; Max., maxillary; Pa.,
parietal; Pmx., premaxillary; p.t., posttympanic process of squamosal; S.oc., supraoccipital; s.or.pr., supraorbital process of frontal;
Sq., squamosal; zyg., zygomatic process of squamosal.
LATERAL VIEW.— The parietals and frontals constitute a
major portion of the lateral walls of the elongated braincase
(fig. 34). Both squamosals are fairly complete. Ventrally,
in the temporal fossa, the squamosal anteriorly meets the
alisphenoid edge to edge. From this point the sutural
contact between the squamosal and parietal extends
obliquely upward and backward to the level of the top of
the braincase where this bone overlaps the anterior edge of
the supraoccipital. The posttympanic process of the squa-
mosal is prolonged ventrally beyond the level of the basi-
cranium but apparently is not ankylosed to the paroccipital
process, which is conjoined with the exoccipital.
The temporal fossa is also elongated and is continuous
anteriorly with the orbital cavity. This temporal fossa is
bounded externally by the zygomatic arch whose major
portion is contributed posteriorly by the elongated and
laterally compressed zygomatic process of the squamosal.
The jugal underrides the anterior end of the zygomatic
process.
Each frontal is produced anteriorly into a rather stout
and narrow supraorbital process, directed obliquely forward
and outward in front of the temporal fossa to form the
roof of the orbit. The orbital cavity has an unusually
thick rim in front and below, which is contributed by the
large jugal. On this fossil skull no vestige of a postorbital
process is developed to even partially delimit the orbit
posteriorly. Underneath the zygomatic process of the
squamosal, the attenuated posterior portion of the jugal
is extended backward as far as the shallow glenoid fossa.
The jugal is a rather long bone (length 168 mm.), whose
anterior portion is bent almost at right angles to the
posterior horizontal portion. This bone constitutes the
ventral rim of the orbit and its anterior end is intimately
pressed against the external surface of the premaxillary.
On the right side, the small, tumid, reniform shaped
lachrymal bone, 42 mm. long dorsoventrally and 18 mm.
wide, is wedged (pl. 33, fig. 2) in against the dorsal end of
the jugal, the premaxillary and the anteroexternal angle
of the supraorbital process of the frontal. A tonguelike
process of uncertain homologies projects backward into the
orbital from the posterior face of the lachrymal.
On the left side of a dugong skull (USNM 284443) from
Coburg Peninsula, Australia, the lachrymal is wedged in
between the dorsal end of the jugal, the premaxillary
internally, and the supraorbital process of the frontal
posteriorly; anteroventrally behind the large infraorbital
foramen, the lachrymal is unquestionably suturally in
contact with the ascending posterior end of the maxillary.
The sutural contacts of the several cranial bones on this
skull are unusually distinct. Lachrymal bones of similar
dimensions and relations to adjacent bones are retained on
dugong skulls from east Africa (USNM 197900) and
Australia (USNM 73331, USNM 28449). On other Aus-
tralian skulls the gap corresponding to the position of the
lachrymal bone is present, although the bone has been dis-
lodged on both sides during maceration. Although greatly
enlarged the relative position of the lachrymal on the
Calvert skull (USNM 16757) is the same, except that
the dorsal end of the jugal has been anteroposteriorly
compressed.
Flot (1886, p. 510) describes the lachrymal of Metaxy-
therium cuvierii as a nearly triangular bone, 32 mm. long
and 15 mm. high whose posterior border descends vertically
from the supraorbital process of the frontal and joins in
NEW SPECIES OF EXTINCT MIOCENE SIRENIA 75
front the jugal and the maxillary. On the type skull
of Halianassa [=Metaxythertum] vanderhoofi, according to
Reinhart (1959, p. 33; see also pp. 57-58), the lachrymal
is 30 mm. long dorsally and 32 mm. high anteriorly.
On the floor of the orbital cavity, the internal surface
of the jugal is suturally united with the external palatal
projection of the maxillary. The jugal of this fossil skull
is relatively much longer and less semicircular in curvature
than that of the Recent Dugong dugon (USNM 284443).
The temporal fossa is more elongated than that of the
Recent dugong. The zygomatic process is robust, com-
pressed from side to side, attenuated toward the anterior
end and rounded posteriorly. The postglenoid process is
short, blunt, and bent inward. The maximum vertical
diameter of the right zygomatic process is 48 mm. On
the anterior half of its length, the zygomatic process of the
squamosal overrides and is applied ventrally to the jugal
and is terminated anteriorly behind the level of the post-
orbital angle of the supraorbital process of the frontal.
As viewed from the right side the vertical diameter of
the posterior half of the premaxillary is approximately
one half the maximum diameter of the bent downward
distal end. The external border of the maxillary portion
of the palate is partially destroyed.
VENTRAL view.—The entire left maxillary (pl. 34, fig. 1)
is missing. On the right side, although the internal border
is eroded, the major remnant preserved shows that the
maxillary extended forward to or slightly beyond the level
of the presumed location of the incisive foramina. This
anterior portion of the maxillary and its external palatal
projection, and the jugal enclose the very large infraorbital
foramen. Posteriorly each premaxillary rests upon a dorsal
prolongation of the corresponding maxillary above the
infraorbital foramen.
There is no evident roughening of the ventral surface of
the right maxillary for attachment of a horny plate. The
state of preservation of the adjacent bones does not permit
accurate determination of the presence or extent of a
median anterior palatal or incisive foramen.
The anterior narial apertures of the choanae are enclosed
on each side of the midline by the ascending or posterior
end of the dorsal extension of the maxillary which sheathes
the undersurface of the premaxillary in front of the supra-
orbital process of the frontal. The anterior narial chamber
was noticeably narrower than that of the dugong. The
vomer forms the roof of the choanae, and sheathes as well
the ventral surface of the presphenoid. The vomer appar-
ently did not extend forward to the level of the anterior
end of the row of cheek teeth. The olfactory chamber
into which the olfactory nerves enter at the rear is greatly
compressed from side to side and contains in this fossil
skull remnants of the thin longitudinally arranged
ethmoturbinals.
The palate, located between two parallel rows of 3 or 4
cheek teeth, seems to have been relatively wider than that
of the dugong and is formed by the pair of maxillaries.
The palatal portions of the maxillaries seemingly did not
extend backward much beyond the posteriormost molar.
On the skull of the Recent dugong the pair of rather
small palatine bones are visible in the palate between the
posterior molars. This region is, however, missing on this
fossil skull.
Behind each row of cheek teeth on the Recent dugong
skull is a prominent and large descending process, formed
by the coalescence of the palatine, with the more or less
vertical platelike pterygoid and the pterygoid plate of the
alisphenoid (external pterygoid of some authors). Each
pterygoid bone is thus wedged in between the alisphenoid
and a similarly descending process of the basisphenoid.
The posterior face of each of this pair of descending proc-
esses is deeply grooved from base to extremity and this
may correspond to a pterygoid fossa. On this fossil skull,
however, this ventral extension of the basisphenoid, alisphe-
noid and pterygoid is broken off at the base on both sides,
but the relations of the more dorsal portion of these bones
are essentially the same as on the Recent dugong skull.
No remnants of either the palatines or the projecting
pterygoids are preserved.
On the roof of the choanae of this fossil skull, the vomer
overspreads the presphenoid and extends relatively much
farther forward than on the dugong skull. The anterior
end of the presphenoid is broken off.
Length of skull, occipital condyle to extremity of pre- 340
maxillary
Length of frontal (midline posteriorly to level of anterior 137
angles of supraorbital processes)
Length of left premaxillary 190
Length of premaxillary symphysis 84
Length of mesorostral fossa 150
Maximum width of mesorostral fossa 53
Width across supraorbital processes of frontals 131
Least intertemporal constriction across frontals 67
Zygomatic width 215
Length of right zygomatic process 140
Maximum vertical diameter of right zygomatic process 57
Length of right jugal 164
Width across posttympanic processes of squamosals 186
Maximum width of supraoccipital 95
Maximum vertical diameter of occipital condyle 36
Maximum transverse diameter of occipital condyle 23
Maximum length row of three upper molars 68.5
Length of first upper molar 18.5
Width of first upper molar 19.6
Length of third upper molar 28.5
Width of third upper molar 18.5
76 UNITED STATES NATIONAL MUSEUM BULLETIN 247
The basicranial axis is thick and the suture between the
basioccipital and basisphenoid is not ankylosed on this
skull.
Behind each of the descending processes of the contiguous
alisphenoid and basisphenoid, the constricted basioccipital
internally, the alisphenoid anteriorly, the squamosal exter-
nally, and the exoccipital posteriorly enclose a large open-
ing or recess which is only partially occupied by the
tympanic half ring and the periotic.
The zygomatic process of the squamosal is rather massive
and long, as well as flattened on the external and internal
faces. Behind the level of its postglenoid process a robust
downward-directed posttympanic process of the squamosal
approximates the thickened exteroventral border of the
exoccipital, forming a paroccipital area for the attachment
of a stylohyoid. Internal to this posttympanic descending
process, between the squamosal and the exoccipital, is a
gap in the cranial wall which is filled by the periotic.
Measurements (in mm.) of the skull of USNM 16757 are
as tabluated above, on page 75.
Ear Bones
TYMPANIC HALF RING.—On this Calvert sirenian skull
both tympanic half rings are detached although on both
periotics the point of attachment of the anterior limb is
better developed than that for the posterior limb (see also
description of sirenian middle ear by Robineau, 1965).
The tympanic half ring (pl. 35, fig. 9) is solid and dense,
and open dorsally; the short, broad, subtriangular, and
nearly straight anterior limb is bent upward almost at right
angles to the more slender curved posterior limb, forming
an obtuse-produced angle at the bend. In general config-
uration this half ring resembles that of Halitherium schinzi
(Lepsius, 1882, pl. 2, figs. 12-13). This tympanic half ring
was apparently rather feebly attached at both ends to points
near the external border of the periotic. Both half rings
were preserved with this skull, although the left one lacks
the extremity of the posterior curved limb.
Periotic.—The right periotic is well preserved but the
internal half of the left one is broken off and missing. ‘This
somewhat peculiar periotic (pl. 36, fig. 3) is a large and
dense bone which is not ankylosed to any of the bones
surrounding the tympanoperiotic recess. It consists of a
hemispherical inner protuberance, the pars Jlabyrinthica
(cochlearis), a rounded dorsoventrally compressed anterior
portion, which is lodged in a cavity in the squamosal, and a
posteroexternal mastoid portion, which bridges the gap
between the exoccipital, the supraoccipital, and the squa-
mosal, and thus forms part of the posterior wall of the
braincase.
Externally, the periotic is abruptly truncated, and thick-
ened dorsoventrally (39 mm.), constituting the mastoid
PART 3
portion. A well developed transverse ridge merging in-
ternally with the pars labyrinthica and postero-externally
with the mastoid portion of the periotic separates the vesti-
bular recess from the rather large depression in which the
fenestra rotunda opens on the posterior face of the labyrin-
thine portion. The fenestra ovalis is situated on the anterior
side of this ridge at the base of the pars labyrinthica. The
periotic is lodged securely anteriorly and externally by the
projecting rim of the squamosal and its descending post-
tympanic process. The anterior portion of the periotic to
which the anterior limb of the tympanic half ring was
attached is markedly compressed dorsoventrally as con-
trasted with the posterior enlargement or mastoid portion
to which the posterior curved limb of the tympanic half
ring was attached. The anterior portion of the periotic is
partially set off from the postero-external mastoid portion
by a deep notch, similar to the condition observable on the
dugong periotic, where this notch or groove is situated ex-
ternal to the point of attachment of the anterior limb of the
tympanic half ring. —The maximum transverse diameter of
the right periotic is 53 mm.
Auditory Ossicles
As regards these small bones of the inner ear, the malleus
was not preserved for either ear region. The right and left
incus are present as well as the right stapes.
Incus.—The right incus (pl. 36, fig. 3) is still lodged on
the tympanic face of the right periotic in contact with the
stapes. The left incus (pl. 35, fig. 10) was detached when
found. In configuration this incus is quite similar to that
of Halitherium schinzi (Krauss, 1862, pl. 6, fig. 5). The
body of the incus is prolonged into the bent or curved crus
longum which articulates with the head of the stapes by an
ovoidal flat facet located on the side below its extremity.
The crus breve is short, conical, and projected upward; the
small facet on its extremity should rest in the fossa incudis
which, however, was not recognized on the tympanic face
of the left periotic. A short blunt nipple-like tubercle is
located internal to the small concavity which serves for
reception of the head of the malleus. From the head of
the crus longum to the base of the body the incus measures
13 mm., and the greatest diameter of the flattened base
is 10 mm.
SrapEs.—The stapes (length, 9 mm.) has the same form
as in Halitherium schinzi (Krauss, 1862, pl. 6, fig. 5). The
small intercrural aperture is located above the footplate and
opens into an ovoidal cavity, presumably on both sides.
The footplate of the stapes, which is lodged in the fenestra
ovalis (pl. 36, fig. 3), is about three times as wide (7 mm.)
as the extremity (2.5 mm.) of this little ear bone. A scar
or roughened area is discernible on the posterior surface
below the articular facet on the extremity or head and may
represent the area for attachment of the stapedius muscle.
NEW SPECIES OF EXTINCT MIOCENE SIRENIA U7
The facet for contact with the facet on the crus longum of
the incus seems to be placed obliquely on the head of the
stapes.
Mandible
As compared to Dugong this mandible (pl. 37, fig. 10)
is more elongated and the coronoid process, which is like-
wise inclined forward, is more elevated. Hatt (1934, p. 553)
has noted that high variation in the shape of the coronoid
process occurs among Trichechus mandibles and hence due
allowance for variability should be made for mandibles of
Metaxytherium. The condyle, which is broken off, appar-
ently was rather narrow. The length of the right mandible
is 255 mm. The ventral profile of the horizontal ramus
is broadly concave. An increase in the depth of the symphy-
sis of an old adult would undoubtedly accentuate the curva-
ture of the ventral profile.
FiGURE 35.—Right mandible, USNM 16757, of Metaxytherium
calvertense. Abbrs.: c., condyle; cor., coronoid process; cm.,
external orifice of mandibular canal.
The anterior ends of the two mandibles of this immature
sirenian were not ankylosed firmly on the symphysis. This
thickened symphysis, however, is truncated obliquely at the
extremity. Internally the large mandibular canal is open
to within 32 mm. of the posterior margin of the symphysis.
Externally the same broad canal is open for a distance of 85
mm. to the extremity of the symphysis.
Alveoli for the roots of at least three cheek teeth are
partially preserved on the mandible of the immature sirenian
(USNM 16757). Juvenile Recent dugongs have four pairs
of slender conical teeth lodged in alveolar cavities which
are concealed beneath the horny plate covering the down-
ward deflected and squarely truncated symphysial ends of
the mandibles. These teeth are absorbed before maturity.
Immature and even old adult dugongs retain these alveoli
partially filled with osseous replacement. Three dorsal
pairs and one ventral pair at the end of the symphysis is
the normal complement. One specimen (USNM 284458)
has four dorsal pairs and one ventral pair and another
(USNM 284456) has three alveoli on the right side and
four on the left side of the dorsally placed alveoli and the
usual one ventral pair. The ventral pair of alveoli are
located at or below the level of the external orifice of the
large mandibular canal.
The large capsule (anteroposterior diameter, 24 mm.)
below the alveolar surface of the horizontal ramus, above
the mandibular canal and in front of the anterior border of
the coronoid process serves as a receptacle for the roots of
the large M; (pl. 37, fig. 10). Alveoli for one premolar
and three molars are present on both mandibles for the
young individual (USNM 16630). The four pair of par-
tially closed alveolar cavities present on the anterior face
of the symphysis of the young individual (USNM 16630)
and present as well on the symphysis of the Recent Dugong
(USNM 284441) are partially obliterated by surface disin-
tegration on the symphysis of the immature sirenian (USNM
16757). Although the ventral portion of the symphysial
region of this immature sirenian is missing, there is exposed
in each mandible below these anteriorly located alveoli an
anteroposteriorly directed groove approximately 15 mm. in
width which opens on the anterior face of the symphysis.
Openings for this pair of grooves, however, are not present
on the anterior face of the symphysis of the young individual
(USNM 16630), but seem to correspond in position to the
partially closed ventral pair of alveoli on the end of the
symphysis of the Recent Dugong (USNM 284441). Alveoli
for two incisors at the end of the mandible of Halianassa
[=Metaxythertum] vanderhoofi are mentioned by Reinhart
(1959, p. 30).
The depth of the horizontal ramus is proportionately
greater for the mandible (pl. 39, fig. 8) of the young individ-
ual than for the immature sirenian (fig. 35). Furthermore,
the configuration of the mandible of the young individual
resembles more closely that of the adult Dugong than that
of the immature sirenian (USNM 16757). The mandibles
of this young individual (pl. 39, fig. 8) are dense and heavy
and thus differ from those of other young mammals. Meas-
urements of the left mandible of the young individual
(USNM 16630) are as follows: Length, 169 mm.; depth,
condyle to posteroventral angle, 101 mm.; minimum depth
of left horizontal ramus, 49 mm.; depth of symphysis, 70 mm.
Measurements (in mm.) of right mandible of USNM
16757 are as follows:
Anteroposterior diameter (condylar region to extremity) 255
Minimum vertical diameter of horizontal ramus 65
Length of symphysis 80
Vertical diameter of symphysis 75
78 UNITED STATES NATIONAL MUSEUM BULLETIN 247
Dentition
Although no enclosed alveolus for a tusklike incisor is
recognizable at the anterior end of either premaxillary
(USNM 16757), the curvature of the internal face of each
premaxillary does suggest that if these bones were in a
better state of preservation internally the presence or ab-
sence of a tusk could have been ascertained. Consequently,
there is no certainty that tusklike incisors were either
present or absent. No conclusive evidence is available
either to demonstrate that the absence of incisors is not in
this sirenian a sexual character.
Dugongids that possessed large incisor tusks were present
in the western North Atlantic Ocean as early as the Mio-
cene. Attention is here directed to five individuals with
large tusks: (1) the type right premaxillary of Dioplotherium
manigaulti Cope; (2) a left premaxillary (YPM 21334)
obtained during phosphate dredging operations on the
Wando River, S.C.; (3) a heavily worn incisor tusk (USNM
9457; length, 88 mm.; maximum width, 37 mm.) from beds
mapped as Calvert formation at Tar Bay, James River,
Prince George Co., Va.; (4) a tusk (AMNH 9852; length,
170 mm.; maximum width, 40 mm.), probably from left
premaxillary, dredged up by “Western Chief” on the west
coast of Florida near Fort Myers; and (5) a tusk (USNM
23110; length, 166 mm.; maximum width, 38 mm.) from
pit near city limits of Savannah, Ga., presumably Miocene
Duplin marl.
The loss of incisors is regarded by Simpson (1932a,
p. 427) as a character acquired by at least four sirenians.
Absence of incisors is ascribed by Simpson as an outstand-
ing peculiarity of the middle Miocene Hawthorn
Hesperosiren crataegensis. Presence of incisor tusks in the
skull has been regarded by some as a diagnostic character
of the Miocene Metaxytherium, although recently at least
one exception has been recorded. According to Reinhart
(1959, p. 31) the Californian Halianassa [= Metaxytherium]
vanderhooft lacks incisor teeth at the anterior ends of the
premaxillaries.
On the incomplete tusk (length, 150 mm.; maximum
width, 74 mm.; least width, 45 mm.) of Hemicaulodon
effodiens (Cope, 1869, pl. 5, fig. 6), the compressed pulp
cavity is open at the basal end; the cross section at the
broken end shows the osteodentine filling the pulp cavity,
which is surrounded by a thick layer of dentine and it in
turn by a thin circumferential layer of cementum. Annuli-
form ridges on the circumference of the dentine core are
exposed by the flaking off of an area of external cementum.
A single large longitudinal groove is present on the external
face of the tusk. All of the above described characteristics,
with exception of the dimensions, can be matched by a
Calvert tusk (USNM 8457) as well as by a Florida Tertiary
tusk (AMNH 9852). It is now suggested without hesita-
PART 3
tion that the type tooth was not derived from the middle
Eocene Shark River marl. Tusklike incisors of similar
dimensions and configuration made their appearance in
sirenian developmental history at a time later than the
Eocene. Inasmuch as the Miocene Kirkwood formation
overlaps the Shark River marl (Manasquan formation),
the association of any specimen picked up on the surface
alongside or in a marl pit being worked could readily be
misinterpreted. The dimensions of the type tusk of
Hemicaulodon effodiens ' correspond more closely with those
of the Aquitanian Rytiodus capgrandi than with those of
other American extinct dugongids.
On the right side of the skull (USNM_ 16757)M! has a
well worn crown (pl. 34, fig. 2), alveoli for three roots
indicate the size of M?, and the more elongated M® is
not fully erupted. If Pm* was present in the young, its
alveolus has now been obliterated by closure. The length
of the maxillary molar row is 68.5 mm.
It should be noted, however, that the young of the
Pliocene (Plaisancian) Felsinotherium serresti (Depéret and
Roman, 1920, p. 8) possessed five upper cheek teeth, two
premolars and three molars, but Pm® disappeared in the
adult and its alveolus is completely obliterated.
The Tortonian Thallatosiren petersi (Sickenberg, 1928,
p. 315) has retained in the upper dentition two premolars
and three molars.
Adults of the Helvetian Metaxytherium medium (cuvierii)
have four upper cheek teeth, one premolar and three molars
(Flot, 1886, p. 509) and this formula is recorded also in two
maxillaries obtained at Doué, France (Cottreau, 1928,
p. 10). The number of upper cheek teeth present in the
middle Miocene (Hawthorn formation) Hesherosiren cra-
taegensis is known with less certainty, not more than five
and possibly only four (Simpson, 1932a, p. 428).
On the palate of the lower Miocene (Burdigalian)
Halianassa studert four cheek teeth are in place in addition
to four root cavities of one or two missing anterior teeth.
The upper dental formula of this sirenian has been inter-
preted to be: Pm?, Pm%, Pm‘, M1, M?, M® (Depéret and
Roman, 1920, p. 33).
Seven upper cheek teeth, three premolars and four molars,
were retained by the middle Oligocene (Stampian) Hall-
therium schinzi (Krauss, 1862, p. 20, pl. 6, fig. 2).
An indentation on the lingual and buccal sides of the
well-worn crown of M! marks the location of the transverse
valley. It is obvious then that the anterior portion of the
crown (pl. 34, fig. 2) is slightly larger than the posterior,
and that the latter is narrower. An incompletely closed
enamel ridge marks the location of the buccal paracone. A
1The type specimen of Hemicaulodon effodiens was purchased in
March 1886 from the Reverend Samuel Lockwood, Keyport, N.J.,
by Professor O. C. Marsh for the Peabody Museum, Yale University.
This specimen cannot now be located in the museum collection.
NEW ‘SPECIES OF EXTINCT MIOCENE SIRENIA
large deep lake is present in the area occupied by the pro-
tocone and protoconule. An enamel rim encircles the
deep lake occupied by the hypocone and metaconule be-
fore they were obliterated by excessive wear. A very small
lake with complete enamel rim represents the remant of
the metacone. Wear has not completely reduced the cin-
gular cusps.
The length (28.5 mm.) exceeds the maximum width (18.5
mm.) of M? anteriorly. The protocone (pl. 34, fig. 2) is
the largest cusp and projects beyond the level of the apices
of the protoconule and paracone. At the apex the proto-
conule and paracone are almost equal in size. An anterior
crest connects the protocone, the antero-internal cusp, with
the anterior cingulum. A low parastyle on the anterior
cingulum is separated from the paracone by a shallow
cleft. Between these elevations on the anterior cingulum
and the transverse row, the protocone, protonconule and
paracone, is a deep lake. From a posterior view, both the
paracone and the protoconule are seen to be inclined
obliquely toward the protocone, and are separated by a
deep unobstructed transverse valley from the cusps on
the posterior half of the crown.
The metaconule, although in advance of the hypocone,
is actually situated much nearer the lingual than the buccal
side of the crown. A narrow almost vertical reentrant
oblique cleft separates these two cusps on the medial or
external side, although they appear to be confluent on the
lingual side. The buccal metacone (pl. 35, fig. 2) is situ-
ated opposite the hypocone, but set off from the latter by
a deep anteroposterior cleft, and is inclined obliquely
inward. A rather large cusp, which may represent another
conule, is not completely separated from the metacone in
front of it. In addition a sharp-pointed low smaller cuspule
is situated medially on the posterior cingulum. A cleft of
varying depths, incompletely obstructed between opposite
cusps, extends backward obliquely from the transverse
valley to the deep lake in front of the posterior cingulum.
79
This Calvert M? does not resemble very closely the
corresponding molar of the Helvetian Metaxytherium cuvierit
[=M. medium] from Chazé-Henry, France (Flot, 1886, p.
502, pl. 27, fig. 2). The illustration of the three molars
published by Flot seems to have been reversed by the
engraver. Measurements (in mm.) given for these three
molars (Flot, 1886) are:
length width page
M! 18 20 503
M2 26 21 502
M3 23 22 503
Any close resemblance to the Calvert sirenian in the place-
ment of the cusps on the crowns of these molars is not
readily apparent.
Simpson (1932a, p. 449) and Gregory (1941, p. 36) have
both commented on the excessive wear of the M! on a skull
of Felsinothertum ossivallense before the M? had fully erupted.
A similar condition exists on this Calvert skull. It will be
observed (pl. 34, fig. 2) that this incompletely erupted
third upper molar is implanted in an alveolus at the pos-
terior end of the maxillary, and that space for a more pos-
teriorly situated alveolus can not be developed in this
portion of the maxillary in view of its sutural contact with
the descending process of the pterygoid.
In the tabulation below are compared the measurements
(in mm.) of the molar teeth of M. calvertense (USNM 1675),
M. medium (Flot, 1886, pp. 502-503), F. ossivallense (Fla.
V. 5454), and M. floridanum (USNM 7221).
Reentrant angles in the encircling enamel rim on the
buccal side of the well worn isolated left M? (USNM 23281)
are interpreted as indicative of the boundaries of original
cusps. The upper reentrant angle (pl. 35, fig. 3) on the
buccal side separated the paracone and the small anterior
parastyle. Between this reentrant angle and the median
wider one the enamel rim follows the outer contour of the
paracone. The wider median reentrant angle is the
Molar Teeth:
Length M! to M3
Length M?
Width M1}, across protocone
Width M!, across hypocone
Length M?
Width M2, across protocone
Width M2, across hypocone
Length M?
Width M3, across protocone
Width M3, across hypocone
Length M3/width M3, across protocone
Metaxytherium Metaxytherium Felsinotherium Metaxytherium
calvertense medium ossivallense floridanum
(USNM 16757, (Flot, 1886, pp. (Fla. V. 5454) (USNM 7221,
type) 502-503) type)
68.5 68 78 7+
18.5 18 1o-++ =
19.6 20 12+ =
15.5 14 — —
— 23 28 ==
— 22 26.2 —
a 17 = =
28.5 26 30.1 27.5
18.5 21 24.2 26.4
18.5 — 22 21.5
1.54 1.24 1.24 1.04
80 UNITED STATES NATIONAL MUSEUM BULLETIN 247
remnant of the transverse valley, which limited the meta-
cone anteriorly. A much narrower reentrant angle
separated the metacone from the cuspidate posterior cin-
sulum. The lingual side of the crown, however, is worn
down below the level of the former reentrant angles. This
M3 has three roots, one anterior and two posterior but
united for most of their length. Measurements of this
right M® are as follows: length, 27 mm.; width across
protocone, 22 mm.; width across hypocone, 17.5 mm.;
length-width ratio, 1.227.
Another detached left M? (USNM 23409) has the roots
completely sheared off at the level of the base of the enamel
crown. The dentine within the enamel crown has not
been resorbed and there remain exposed a pair of cavities
for the nerves and vascular vessels which were within the
roots. This tooth (pl. 35, fig. 1) appears to have been in
the permanent dentition since this sheared off crown does
not possess the characteristic appearance of the hollow
enamel crown of the shed deciduous molar teeth of the
young sirenian (USNM 16630) hereinafter described.
A large unworn paracone is separated by a thin cleft from
the worn apex of the protoconule, the rim of which is con-
tinuous with the rim of the abraded protocone. A large
deep narrow lake lies between the anterior cingulum and
the three cusps in the transverse row. The narrow and
deep transverse valley is deflected by the forward thrust of
the worn apex of the hypocone beyond the worn apices of
the metaconule and the worn rim of the metacone. The
cleft behind the hypocone and the metaconule is continuous
posteriorly with the constricted lake in front of the cuspi-
date posterior cingulum. The measurements of this molar
are as follows: length, 25.2 mm.; width across protocone,
21 mm.; width across hypocone, 18.5 mm.; length-width
ratio, 1.20. A constant crown pattern is not readily dis-
cernible when comparison is made of the third upper
molar of three individuals (USNM 16757, 23281, 23409).
An isolated left Mz (USNM 23271) discovered in zone 11
of the Calvert formation one mile south of Plum Point
wharf, Md., has two wide roots, one anterior and the other
posterior. This molar (pl. 35, fig. 4) has a crown width
anteriorly of 15 mm. and a length of 21 mm.; the height of
the crown and posterior root is 36 mm. Wear has com-
menced on the enamel on the crown, obliterating a trans-
verse valley between the protoconid and metaconid
anteriorly, and the hypoconid and entoconid posteriorly.
The metaconid projects forward slightly in advance of the
protoconid. The summits of the protoconid and metaconid
are worn down effacing the usual separation between them
and the more centrally located anteromedian cuspule or
plica. On the buccal side the anterior talon is greatly
reduced.
Between the hypoconid and the entoconid, the postero-
median cuspule is situated centrally across the original trans-
PART 3
verse valley. On the buccal side the hypoconid is also smal-
ler than the entoconid on the lingual side. At the rear of the
crown of the left M, tooth on the buccal side is a worn
conule which is regarded as the hypoconulid. Internal to
this cusp are two worn secondary conules on the posterior
border of the cingulum. Depéret and Roman (1920, pl. 7,
fig. 2a) illustrated the cheek teeth in the right mandible of
Metaxytherium cuvierti [=M. medium] excavated at Chazé-
Henry, Maine-et-Loire, France. Differences seemingly not
of generic importance between the Mg of Metaxytherium
medium and the Calvert sirenian are observable.
In the left mandible (pl. 35, fig. 7) of the young sirenian
(USNM 16630) the anteriormost cheek tooth is represented
by an empty alveolus for a single root; two roots of the second
cheek tooth, sheared off at the alveolar level, are lodged in
the alveolus for the second lower cheek tooth; the crown of
the two-rooted penultimate cheek tooth is very slightly
abraided, and the alveolus for two wide roots of the pos-
teriormost tooth is empty. In the right mandible the
anteriormost alveolus is essentially obliterated by closure,
the alveolus for the two roots of the second tooth is empty,
the enamel crown of the penultimate cheek tooth is slightly
worn, and the enamel crown of the posteriormost cheek
tooth is certainly unworn. One hollow crown of the
deciduous molar, which was being shed, overlay the unworn
crown of this posteriormost cheek tooth in the right mandi-
ble. The large osseous cuspule which later in life will con-
tain the roots of the lower M; was empty in both mandibles;
the dorsal aperture of this cuspule is small and irregular
in outline.
On the right penultimate lower cheek tooth (pl. 35, fig.
8) a transverse valley separates the anterior portion of the
crown with its large metaconid and smaller protoconid
from the posterior worn portion of the crown with confluent
hypoconid, entoconid and posteromedian cuspule or plica.
The posterior talon is large and minutely cuspidate; this
portion of the crown is less abraded. The length of the
crown of this tooth is 13.5 mm., and its width, 11 mm.
The posteriormost cheek tooth measures 17 mm. in length
and 12 mm. in width. The crown of this cheek tooth
(pl. 35, fig. 8) shows no evidence of wear. The summits of
the protoconid and metaconid are not confluent; this ante-
rior portion of the crown is likewise sharply separated from
the posterior portion by a deep transverse valley. This
transverse valley is partially bisected centrally by the low
longitudinal ridge that connects the anterior and posterior
median cuspules. The posteromedian cuspule is located in
part anterior to the hypoconid, which in turn is separated
by a narrow cleft from the entoconid on the lingual side of
the crown. On the buccal side the posterior talon seems to
give origin to a hypoconulid, which is separated by a deep
cleft from the hypoconid (fig. 36).
NEW SPECIES OF EXTINCT MIOCENE SIRENIA 81
The upper and lower molars have few trenchant differ-
ences, usually the anterior lake of the posterior upper molars
is rather large and the main cusps are well developed. The
anterior lake of the posterior lower molars is reduced and
the main cusps are less prominent.
Regressive processes associated with the erupting per-
manent or succeeding cheek tooth resulted in the entire
absorption of each milk tooth except the hollow cuplike
enamel crown. The enamel crowns (pl. 35, figs, 5, 6) of
the two opposite deciduous cheek teeth each measure 18
mm. in length and 13 mm. in width. They are here
regarded as the third lower deciduous cheek teeth. For
these milk teeth (USNM 16630) the terminology of the
permanent molar is applied topographically in view of the
uncertain homologies of the cusps on the crowns of the
deciduous cheek teeth.
Ficure 36.—Posteriormost lower cheek tooth, right mandible,
USNM 16630, of Metaxytherium calvertense.
entoconid; Hy%, hypoconid; Hyc%,
metaconid; Pr®, protoconid.
Abbrs.: En4,
hypoconulid; Med,
The buccal protoconid and the opposite metaconid are
both bluntly conical and are partially separated by a
shallow narrow cleft. The small anteromedian cuspule
is pressed against the protoconid and also partially ob-
structs the deep transverse valley centrally. The entoconid
is slightly smaller than the hypoconid; these two conids
are so closely approximated that they tend to conceal the
posteromedian cuspule. The large buccal hypoconulid
is cut off from the hypoconid by a deep cleft. The posterior
talon located on the lingual side of the hypoconulid is
noticeably cuspidate.
No plausible explanation has been advanced to support
the contention of Lepsius (1882, p. 106) that sirenian cheek
teeth increase in size during advancing age. It is generally
_ accepted that once the enamel crown is fully formed any
size increase of cheek teeth is terminated. Thomas and
Lydekker (1897) have described and figured the continuous
succession of cheek teeth in the Recent manatee (J7-
chechus). They have shown that as regards the mandibles
of Trichechus senegalensis the anterior eroded cheek teeth are
thrown off during growth, with the consequent increase in
the length of the upper and lower jaws, and that the replace-
ment teeth developing in the jaw at the posterior end of
the row will be erupted sequentially (see also Heuvel-
mans, 1941). This method of replacement of worn off
and shed cheek teeth may suggest at least one explanation
of the diminutive size of the teeth of the young Calvert
sirenian, which are so much smaller than those in the im-
mature skull or isolated teeth of adults.
As regards the Oligocene Halitherium, however, the de-
scribed specimens (Krauss, 1862, pl. 6; Lepsius, 1882, pl.
10, fig. 96) also show an observable tendency toward pro-
gressively heavy wear of the upper cheek teeth from before
backwards. Nevertheless, on these mentioned skulls the
posteriormost cheek tooth is fully erupted and wear has
commenced, but no indication of a developing replacement
molar is visible. On a left mandible (Lepsius, 1882, pl.
4, fig. 32), however, similar progressive wear of the lower
cheek teeth from before backwards is observable, but the
hindmost molar has not fully erupted. Mention should
be made that no small young individual of Halitherium of
a size comparable to the young Calvert sirenian has been
illustrated or described. Related observations according to
Abel (1906, pp. 59-60) show that the fourth milk molar
is retained unusually late in life by the Halitheriidae and
is sometimes intercalated between the posteriormost succes-
sional premolar and the first true molar (see also Heuvel-
mans, III, 1941, p.6). By this interpretation Abel explains
the presence of eight postcanine teeth in the mandible of
Halitherrum schinzz, an interpretation which does not re-
quire budding from the tooth germ of the third molar
to form an additional molar.
It is quite possible that the observed cheek tooth replace-
ment of Trichechus represents an advanced stage in the
adaptation of the dentition to the excessive wear and that
cheek teeth succession in the Calvert sirenian may have at
least conformed to an intermediate condition that enabled
this vegetable feeding animal during growth toward matu-
rity to replace the small cheek teeth that succeeded the
milk deciduous dentition, by larger molars compatible in
size with adequate mastication requirements. In accord-
ance with such an interpretation, during this sirenian’s
growth the cheek teeth at the anterior end of each jaw may
have been worn out and shed before the posteriormost
cheek teeth were fully developed and erupted.
As an alternative interpretation, the suggestion is here
made that the total number of cheek teeth that erupted
during the life of this Calvert dugongid exceeded the
82 UNITED STATES NATIONAL MUSEUM BULLETIN 247
number that would be required in the majority of mammals
for replacement in the usual diphyodont dentition, a first or
milk dentition and the second or permanent dentition. In
support of this assumption attention is called to the presence
of the large osseous capsule below the alveolar surface of
the horizontal ramus for enclosure of the roots of the
posterior lower molar. This capsule in the mandible
(USNM 284441) of the living dugong contributes a com-
plete osseous shell or wall around the roots of M3 except
for the ventral opening for the nutritive vessels and nerves.
The internal wall of this capsule (pl. 37, fig. 10) on the
right mandible of the immature Calvert sirenian (USNM
16757) has been broken off and destroyed though remnants
of the rims of the alveoli are visible. On each of both
mandibles of the young sirenian (USNM 16630) this cap-
sule is not enclosed by an osseous wall ventrally, and it does
have a dorsal opening which, during growth or ensuant
lengthening of the mandibular ramus, would increase in
size, permit eruption of the molar and serve as the recep-
tacle for the roots of the permanent M3. Since both
deciduous crowns of the posteriormost lower cheek teeth
were preserved with these ankylosed mandibles of the
young sirenian, the rooted lower cheek teeth that remain
lodged in the respective alveoli would necessarily be dis-
placed and replaced subsequently by molars of appropriate
dimensions.
Scapula
Incomplete right and left scapulae were associated with
this skeleton, although the right one lacks only a portion
of the anterior border. The vertebral border of the
anterior half of the left scapular blade, a considerable
portion of the prescapular fossa, the basal portion com-
prising the glenoid articular fossa and the coracoid are not
preserved. From the vertebral margin to the end of the
acromion the left scapula measures 243 mm. and the right
242 mm.
The high spinal crest is very well developed, extending
more than half the height of the blade of the scapula
(pl. 43, fig. 1) and terminating in the relatively large,
slightly bent-backward acromion. This spinal crest
provides a rigid support for the blade. The prescapular
fossa is relatively large, exceeding the postscapular fossa in
area. The curvature of the posterior profile is somewhat
similar to that of Felsinothertum serrestti (Depéret and Roman,
1920, pl. 2, fig. 2).
The basal end of the right scapula of an adult individual
(USNM 23213) is complete. Between the spinal crest and
the glenoid cavity the neck (width, 42 mm.) is narrowed
and a little compressed (28 mm.) exterointernally. The
glenoid cavity is deeply concave and measures 55 mm.
anteroposteriorly and 40 mm. exterointernally. The stout
PART 3
coracoid process is rather short and bent inward, but is
narrower and more strongly exterointernally compressed
than the enlarged and blunt-nosed process of the right-
scapula of the immature individual (USNM 16757).
A left scapula (USNM 16715) of a young individual
measures 199 mm. in vertical diameter and its prescapular
fossa is slightly larger in area than the postscapular area.
The vertebral profile of this scapula (pl. 43, fig. 2) is more
convexly curved than that of the immature individual
(USNM 16757). The spinal crest, coracoid and glenoid
cavity are not materially unlike the immature scapula.
The blade is relatively narrow and curved backward.
Measurements (in mm.) of the scapulae of USNM 16757,
16630, and 16715 are as follows:
USNM USNM USNM
16757 16630 =16715
(Right (Right (Left
immature) young) young)
Vertebral margin to anterior edge 280 198 199
of glenoid articular cavity
Dorsoposterior angle of blade to 205 150 153
posterior edge of glenoid
articular cavity
Posterior edge of glenoid articular 74 47 46
cavity to extremity of coracoid
Vertebral margin of blade to ex-
tremity of acromion
Anteroposterior diameter of 57 38 35
glenoid articular cavity
Humerus
Both humeri of this immature sirenian have the distal or
trochlear extremity damaged; the inner trochlea and capi- |
tellum are broken off as are the outer condyle of the
left and the inner condyle of the right humerus, as well as
the major portion of the coronoid fossa on both. The de- |
tached head of one humerus is preserved but the proximal |
epiphysial ends of both, comprising the greater tuberosity
and the lesser tuberosity, were not found.
Viewed from in front, the shaft of each humerus (pl. 41,
fig. 3) is noticeably narrowed below the greater tuberosity,
the inner profile being more concave than the outer and
it also flares out at the distal end to form the inner condyle. |
The deltoid crest increases in prominence from the coro-
noid fossa to the broad greater tuberosity and tends to fold
over toward the outer face. This crest forms the sharp |
anterior edge of the shaft. The rounded internal face of
the shaft contrasts strongly with the opposite face which is
limited posteriorly by the supinator ridge which, however,
is not sharp edged.
The olecranon fossa (pl. 41, fig. 4) on the posterior face
at the distal end of the right humerus is deep and rather
NEW SPECIES OF EXTINCT MIOCENE SIRENIA 83
broad. The bicipital groove on the proximal end between
the greater and lesser tuberosities is relatively broad and
deep. The detached cap or head is relatively small, as on
other sirenian humeri.
Measurements of left humerus (USNM 16757) are:
length as preserved, 155 mm.; extero-internal diameter of
proximal end, 77 mm.; anteroposterior diameter of proxi-
mal end, 67 mm.; minimum diameter of shaft, 29 mm.
Radius and Ulna
The distal three-fourths of the left radius alone was re-
covered when the skeleton (USNM 16757) was excavated.
The left radius and ulna of a slightly larger individual
(USNM 23213) were separated when found and were
subsequently united (pl. 41, fig. 1) by a museum preparator.
Old adults seemingly have the radius and ulna ankylosed
at the proximal and distal ends (USNM 9346). The shaft
of the radius is bent forward. In cross section the shaft of
two of these radii varies from ovoidal to subcircular. One
radius (USNM 23213), however, has its posterior face
flattened and the anterior face raised longitudinally into a
ridge. A shorter internal crest extends downward half the
length of this shaft. The rugose distal extremity of two of
these radii is subtriangular in cross section and the third is
nearly circular.
The shaft of one ulna (USNM 23213) below the olecranon
is subtriangular in cross section, and a sharp edged longi-
tudinal crest extending downward from the olecranon con-
stitutes the posterior face. On another ulna (USNM 9346)
this crest is not developed. The olecranon process of the
ulna (pl. 41, fig. 2) is short, rather thick and is occupied
anteriorly by the transversely placed sigmoid cavity for
articulation with the trochlear end of the humerus. This
sigmoid articular cavity is continuous with the shallowly
concave articular surface on the proximal end of the radius.
A smaller dorsal or ulnar articular portion of the sigmoid
Cavity on one ulna (USNM 23213) is set off from the wider
and larger portion by a groove. A slight torsion toward the
distal end is observable in the almost straight shaft of the
ulna. The interosseous space between these two forearm
bones is wide and open on one (USNM 9346) and slitlike
on the other (USNM 23213).
The firmly ankylosed radius and ulna (USNM 9346)
from Fairhaven, Md., was described and figured by Case
(1904, p. 56, pl. 26, fig. 1) under the designation Trichechus
giganteus (?) (DeKay).
Pelvis
A right innominate bone (USNM 16757) was associated
with the skull and other skeletal elements. A left innomi-
nate bone (USNM 23213) that lacks the anterior end of
the ilium as well as much of the ischium behind the ace-
tabulum was found among mingled ribs of a somewhat older
individual. Lepsius (1882, pl. 7, figs. 80, 81, 82, 84, 85)
has illustrated the variation in the configuration of this
bone and also in the position of the acetabulum observed
among several specimens. Judging from the two Calvert
innominate bones, similar variability prevailed. The most
complete innominate bone (pl. 41, fig. 5) has a rather
slender ilium, compressed from side to side, slightly ex-
panded at the anterior end and feebly curved inward. The
crista lateralis, if present, is indistinctly developed. An
ovoidal scar on the anterior end of the ilium may indicate
a rather close ligamentous attachment to the extremity of
the sacral vertebra. At the level of the acetabulum, the
shaft of the innominate bone is widened, resulting in the
development of a ventrally directed enlargement which
may represent the reduced pubis. A shallow ovoidal artic-
ular facet for the head of the femur is situated on the
ventral angle of this enlargement. The area where the
acetabular notch was located is deeply abraded. The
ischium is represented by the dorsoventrally widened and
side to side compressed posterior portion of this bone. The
irregular contour of the roughened hinder end of the
ischium may indicate attachment of a cartilage. Measure-
ments of USNM 16757 are as follows: length, 184 mm.;
diameter of distal end of ilium, 20 mm.; and diameter of
end of ischium, 34 mm.
On the left innominate bone (USNM 23213), the ilium
is less compressed from side to side, somewhat oval in cross
section and retains more distinctly the crista lateralis. The
shallow, oval articular facet (pl. 41, fig. 6) for the head of
the femur is located on the external face of the pubic
enlargement, and a distinct acetabular notch is visible on its
internal or ventral border. The surface of the bone
surrounding the acetabulum, although porous and rough-
ened, is apparently not abraded. Just behind the acetab-
ulum the inner surface of the ischium is flattened and this
portion of the innominate bone may have been less widened
dorsoventrally.
The pelvis of the Calvert sirenian has degenerated much
farther than in the Miocene Metaxytherium krahuletzi (Abel,
1904, pl. 7, figs. 3, 4) and also in a slightly different direction
than in Thallatosiren petersi (Abel, 1904, pl. 7, fig. 2a). As
compared to Halitherium schinzi (Lepsius, 1882, pl. 7; Abel
1904, fig. 24), the acetabulum has migrated downward to
or near the ventral face of the pubic enlargement of the
innominate bone.
Sternum
The sternum of Metaxythertum cuvierii is described and
figured by Cottreau (1928, p. 16, pl. 2, fig. 2) asa single
piece of bone, the manubrium being fused with the xiphi-
sternum, The sternum (pl. 41, fig. 7) of the immature
84 UNITED STATES NATIONAL MUSEUM BULLETIN
Calvert sirenian has the manubrium (presternum) separate
from the posterior segment.
The anterior portion of the sternum is spatulate, com-
pressed dorsoventrally at the distal end, the truncated end
being pitted and rugose for a cartilaginous attachment,
and becoming progressively thicker and more convex on
the upper and the lower surfaces. A low longitudinal
ridge is developed on both of these surfaces. This anterior
portion of the sternum also is curved from end to end. A
lateral tuberosity on one side and a roughened area on the
other seem to represent the region of attachment of the
first pair of ribs, as in the Recent dugong. Behind these
rib attachment areas the sternum becomes ovoidal in cross
section (28 44 mm.); the posterior end and the lateral
surfaces adjacent to it are irregularly rugose and porous.
This end may have been contiguous to an intermediate
ossified segment to which the second, third and fourth pair
of ribs were attached as in the Recent dugong, or to the
xiphisternum. No other segments of the sternum were
recognized among the associated skeletal elements. Lepsius
(1882, pl. 6, figs. 73-75) describes and figures three segments
of the sternum of the Oligocene Halitherium schinzt.
Vertebrae
Skeletons of several extinct dugong genera have been
reconstructed for exhibition purposes, including Halitherium
schinzi (Brussels); Metaxytherium medium (Paris; Cottreau,
1928, pl. 1); Felsinotherium serresii (Lyon; Depéret, 1914);
and Hesperosiren crataegensis (New York; Simpson, 1932b).
Estimated lengths of some of these skeletons are as follows:
Halitherium schinzi, 2.58 m., or 8.44 feet (Depéret and
Roman, 1920, p. 37); Metaxytherium medium, 3 m., or 9.8
feet (Cottreau, 1928, p. 7); Miostren kochi, 3.53 m., or 11.54
feet (Depéret and Roman, 1920, p. 25); Hesperostren cratae-
gensis, 3.045 m., or 10 feet (Simpson, 1932b, p. 7); Metaxy-
therium jordani, 4.48 m., or 14.66 feet (Kellogg, 1925, p. 58);
and Felsinotherium serresit, 2.45 m., or 7.98 feet (Depéret and
Roman, 1920, p. 22). The estimated length of the skeleton
of this immature Calvert sirenian is 3.054 m., or 10 feet.
CERVICAL VERTEBRAE.—Seven cervical vertebrae com-
prise the neck of the Recent dugong although the manatee
has only six. Since only an axis and three other cervical
vertebrae in varying states of preservation were associated
with this skeleton, the number in this vertebral series
remains uncertain.
Axis: The configuration of the axis (USNM 16757) is
quite similar to that of Metaxytherium cuviertt (Cottreau,
1928, pl. 2, fig. 1) and its preservation is somewhat better
than the other cervicals. The blunt nipple-like odontoid
process projects forward at least 25 mm. beyond the flat
anterior articular facets for the atlas, which are subcircular
in outline and slope obliquely backward from internal to
external margins. The neural canal (pl. 39, fig. 5) is
247 PART 3
higher (41 mm.) than wide (35 mm.) and rather flat at the
base. The pedicles of the neural arch are almost triangular
in cross section and give origin posteriorly to the post-
zygapophysial facets for articulation with the third cervical.
The roof of the neural arch is thick, bluntly truncated
dorsally and notched posteriorly, but no vestige persists of
a neural spine. The posterior articular face of the centrum
is concave or depressed and is wider (50 mm.) than high
(28 mm.). Other measurements are: maximum height,
90 mm.; maximum width, 81 mm.; distance between outer
margins of postzygapophysial facets, 71 mm.; and maximum
width of neural canal, 35 mm.
Fourth Cervical: This cervical has a thin centrum (thick-
ness, 12 mm.), its anterior face concave and its posterior
face convex, its width posteriorly (67 mm.) greater than
its height (30 mm.), and has its large winglike transverse
processes (pl. 39, fig. 6) pierced near the base by the verte-
brarterial canal. These transverse processes project more
outward than downward and are curved slightly backward
externally and bent forward ventrally below the level of
the centrum. The pedicles of the neural arch are slender
and compressed anteroposteriorly. The right postzygapo-
physial facet on the undersurface of the prezygapophysial
facet is ovoidal; the flat prezygapophysial facet is located
dorsally on the right pedicle and slopes obliquely downward
from external to internal margin. The maximum width of
the neural canal is 48 mm. The distance between external
angles of the transverse processes is 121 + mm.
Fifth Cervical: A portion only of the centrum of this
cervical is preserved. The height of the centrum is 33
mm. and its thickness 12 mm. The origin of the trans-
verse process on the lateral surface of the centrum is lower
than on the sixth cervical.
Sixth Cervical: The thickness (16 mm.) of this cervical —
has increased slightly over the preceding centra. The
width (62 mm.) of the centrum posteriorly is nearly twice |
its height (32 mm.). The broad and rather thin transverse |
processes, which are projected more outward and forward
than upward, actually curve backward toward the extrem-
ity. Each process (pl. 39, fig. 7) has its origin considerably
higher on the lateral surface of the centrum than on the
preceding cervical and is pierced dorsally below the pre-_
zygapophysial facet by a large vertebrarterial canal. An
interval of 72 mm. separates the opposite prezygapophysial |
facets. Each prezygapophysial facet slopes slightly down- |
ward from external to internal margin, terminates poste-
riorly in a depression on the neural arch and projects
forward beyond the level of the transverse process which
contributes to its support. The roof ofthe neural arch is
thin, weak and bent backward. No vestige of the neural
spine persists. Each postzygapophysial facet is situated for
the most part on the undersurface of the corresponding
NEW ‘SPECIES OF EXTINCT MIOCENE SIREINIA 85
prezygapophysial facet. The width of the neural canal is
51 mm.; and height 43 mm. The distance between the
external angles of the transverse processes is 139 mm.
DorsAL VERTEBRAE.—Forty ribs, representing the right
and left sides of the thorax, were excavated in association
with this skeleton although sixteen dorsal vertebrae were
located. Nineteen vertebrae (Cottreau, 1928, p. 13) com-
prised the dorsal series of the Loire Valley sirenian Metaxy-
therium cuvierti [= M. medium].
The contour of the anterior end of the centrum of con-
secutive dorsals becomes altered from the transversely
widened outline of the first dorsal to a less noticeably dorso-
ventrally compressed subcordate outline near the middle of
this series. A keel is developed or at least becomes more
noticeable on the ninth dorsal. The increase in the length
of the centra behind the eighth dorsal is rather slight and
on all sixteen dorsals excavated the transverse diameter
exceeds the vertical diameter of the anterior end. A few
of these dorsals have the roughened anterior and posterior
ends of their centra coated partially at least with a thin
veneer of bone which may later in life develop as an epiphy-
sis. No distinct epiphyses are discernible on the dorsal
vertebrae of the young of Recent sirenians.
The genera Halitherium, Metaxytherium, Miosiren, Hespero-
siren, and Felsinothercum are now represented in collections
by sufficient portions of the vertebral column to show that
some of the anterior dorsal vertebrae have three pairs of
facets for ribs; a facet at the end of the diapophysis for the
tuberculum of each articulating rib, and two external demi-
facets. The anterior demifacet articulated with the pos-
terior half of the capitulum of the corresponding rib and
the posterior demifacet with the anterior half of the capitu-
lum of the following rib. Anterior demifacets are present
on the first to the eighth dorsal vertebrae of this Calvert
sirenian. On the first dorsal (pl. 37, fig. 1) the shallowly
concave anterior demifacet is located at the anteroexternal
angle of the centrum below the base of the pedicle of the
neural arch. This anterior demifacet is elevated progres-
sively on succeeding dorsals until on the seventh and eighth
it is located wholly on the lateral surface of the pedicle of
the neural arch. This demifacet also increases in size and
depth. The posterior demifacets likewise shift upward in
position from the postero-external angle of the centrum of
the first dorsal to the posterobasal portion of each pedicle
of the neural arch on the eighth to tenth dorsal (pl. 39,
fig. 1). Notwithstanding the presence of these well-defined
posterior demifacets on the tenth dorsal, no recognizable
anterior demifacet on the lateral surface of the pedicle of
the neural arch of the ninth and tenth dorsals was detected.
The first nine dorsal vertebrae of Metaxytherium medium
(cuvieriz) possess anterior and posterior demifacets for artic-
ulation with the heads of ribs according to Cottreau (1928,
p. 13) and the posterior demifacet disappears after the
tenth dorsal. The posterior demifacet was well developed
on the tenth dorsal (pl. 39, fig. 1) of the Calvert sirenian,
but was not present on the twelfth dorsal, the eleventh
being represented solely by the neural arch and neural
spine.
The facet for articulation with the tuberculum of the
corresponding rib on the end of the diapophysis becomes
less sharply defined behind the fourth (pl. 37, fig. 4) in the
dorsal series, although it is quite deep on the tenth dorsal.
On the first (pl. 37, fig. 1) and second (pl. 37, fig. 2)
dorsals, the neural spine is relatively slender, subacuminate
and inclined backward. The five anterior dorsals (pl. 37)
have higher neural spines than those near the middle
of this series, where they tend to become more erect. The
neural spines progressively increase in width anteropos-
teriorly from the first to the fourth (pl. 37, fig. 4) and then
become more noticeably triangular in cross section, wider
posteriorly and more strongly obliquely truncated at the
distal end. On the fifth dorsal (pl. 37, fig. 5) a low, thin,
anteroposterior median ridge or crest makes its appearance
on the distal end of the neural spine, but further develop-
ment or accentuation seems to have been retarded behind
this vertebra.
The longest transverse processes (diapophyses) are devel-
oped on the first dorsal (pl. 38, fig. 1). On all the dorsals
these processes project outward from the pedicle of the
neural arch. The extremity of the diapophysis increases in
thickness as well as in anteroposterior diameter and is bent
more noticeably upward behind the second dorsal (pl. 38,
fig. 2) as far backward as the eighth. From the ninth to
the sixteenth dorsal, the extremity of the diapophysis is
progressively reduced in prominence and tends toward
atrophy on the fifteenth and sixteenth dorsals (pl. 39, fig
4). A deep irregular depression for attachment of the rib
occupies the undersurface of the reduced or vestigial
diapophysis and the pedicle of the neural arch of the
fifteenth (pl. 37, fig. 8) and sixteenth dorsals.
The pedicles of the neural arch become more massive
behind the fourth dorsal (pl. 38, fig. 4), the mmimum
anteroposterior length of the tenth dorsal being 46 mm.
The neural canal decreases in width from the first to the
sixteenth dorsal (pl. 39, fig. 4) and also in height; it becomes
more nearly hexagonal on the twelfth dorsal and the dorsal
notch or groove commences its development on the fifth
dorsal (pl. 38, fig. 5).
On the first seven dorsals, the prezygapophysial facet is
more or less horizontal although it curves upward on its
external borders. On the eighth dorsal to the sixteenth
dorsal of this series this articular facet definitely slopes
obliquely downward from external to internal margin, and
the anteroposterior ridge or crest delimiting its outer mar-
gin increases in prominence. This shift in the inclination
of the facet culminated on the eighth dorsal with the in-
86 UNITED STATES NATIONAL MUSEUM BULLETIN 247
cipient development of the metapophysis which progres-
sively increases in size and height toward the posterior end
of the dorsal series and projects forward beyond the level
of the anterior face of the centrum. The width of the gap
between the prezygapophysial facets decreases from the
first to the sixteenth dorsal and presumably to the end of
this series. On the fourth (pl. 38, fig. 4) to and including
the sixteenth dorsal a deep groove extending backward to
the base of the neural spine bounds the prezygapophysial
facet internally.
The distance between the outer margins of the post-
zygapophysial facets decreases from 77 mm. on the first
dorsal to 46 mm. on the sixteenth. These postzygapo-
physial facets become narrower and slope more obliquely
downward from external to internal margin toward the
hinder end of the dorsal series.
LUMBAR VERTEBRAE.—Four neural arches and their
neural spines associated with this skeleton (USNM 16757)
were presumably detached from centra of lumbar and
sacral vertebrae since the slope and length of the lateral
surface of the pedicle of the neural arch seems to exclude
the existence of even a vestige of the diapophysis. One
lumbar certainly is represented by a detached transverse
process.
Three lumbar, one sacral, and two caudal vertebrae
were associated with the young Calvert sirenian skeleton
(USNM 16630). Cottreau (1928, p. 13) states that three
lumbar and one sacral vertebrae are present in the nearly
complete skeleton of Metaxytherium medium (cuvierii) exca-
vated at Doué-la-Fontaine, France.
The anterior and posterior ends of the centra of these
three lumbar vertebrae (USNM 16630) are transversely
widened and depressed dorsally; two are somewhat flattened
ventrally. All three possess ventrally a median longitudinal
ridge which is rather wide on the first lumbar and quite
narrow on the third lumbar. The elongated transverse
processes (pl. 40, fig. 4) are dorsoventrally compressed and
bent forward near the middle of their length; they project
outward horizontally or slightly downward. The neural
canals (pl. 40, fig. 3) are subtriangular in outline and the
thin pedicles of the neural arch occupy more than half the
length of the centrum.
Rather slender metapophyses with elongated prezy-
gapophysial facets on the first and ovoidal on the third
lumbar project forward beyond the level of the anterior
face of the centrum. The distally rounded neural spines
are rather short, their height above the roof of the neural
canal being less than the distance from the dorsal face of
the metapophysis to the ventral face of the centrum.
Measurements of the third lumbar are as follows: distance
between ends of transverse processes 222 mm.; tip of
neural spine to ventral face of centrum, 108 mm.
SACRAL VERTEBRA.—The sacrum is reduced to one ver-
PART 3
tebra (USNM 16630) which is distinguished from the third
or last lumbar by the dorsoventrally thickened and bent
downward transverse processes (pl. 40, fig. 1), each of which
is expanded at the extremity to provide a flattened surface
for contact with the innominate bone. Otherwise, this
sacral vertebra (pl. 40, fig. 2) is quite similar in general
configuration to the last lumbar vertebra. Measurements
of the sacral are as follows: distance between ends of
transverse processes, 210 mm.; tip of neural spine to ventral
face of centrum, 105 mm.
CAUDAL VERTEBRAE.— Lhe two caudal vertebrae (USNM
16630) possess shorter transverse processes than any of the
three lumbars or the sacral vertebra. The rather broad
transverse processes are directed obliquely downward and
their extremities are rounded. Thin epiphyses are attached
to the posterior ends of their centra and remnants of the
anterior epiphysis are preserved on one caudal. The ends
of the centra are somewhat hexagonal in outline. Below
each transverse process the lateral surface of the centrum
is depressed and the ventral surface is traversed by a broad
median longitudinal trough which is bounded anteriorly
and posteriorly by low almost triangular facets for artic-
ulation with the chevron bones. The neural canal of each
of these caudals is subtriangular in outline and higher than
wide; the pedicles of the neural arch and the neural spines
are reduced in anteroposterior length. As compared to the
sacral vertebra, the height of the neural spine (48 mm.) of
this caudal is almost identical, the vertical diameter of the
neural canal has diminished and the vertical diameter of
the centrum has increased slightly, yet the distance from
the tip of the neural spine to the ventral face of the centrum
(105 mm.) remains unchanged. The slender metapophyses
are smaller than those of the preceding vertebrae, but pro-
ject forward also beyond the level of the anterior face of
the centrum.
The caudal series of the Recent dugong is comprised of
20 to 27 vertebrae and this suggests that more than 20
caudals may have been present in the vertebral column of
this Calvert sirenian.
Measurements (in mm.) of dorsal vertebrae of USNM
16757 are given in the tabulation on opposite page.
Ribs
The Loire Valley Metaxytherium medium has nineteen pairs
ofribs. It is certain that the skeleton of the Calvert sirenian
has one additional pair of ribs. Forty ribs were excavated
with this skeleton (USNM 16757). All of the ribs are
dense, hard and heavy; no internal marrow cavity is
recognizable.
Three processes, two of which bear articular facets, are
present on the vertebral ends of the ribs of the first pair;
two facets are present on the second to twentieth, inclusive.
On the second to the tenth or eleventh pairs of ribs, the
NEW ‘SPECIES OF EXTINCT MIOCENE SIRENIA
87
USNM 16757—Dorsal Vertebrae: Dr D.2 D3
Anteroposterior diameter of 31 36 39 43 46
centrum
Transverse diameter of centrum 91 81 80 76 75
anteriorly including demifacet
for capitulum
Vertical diameter of centrum 30 30.5 32.5 33 35
anteriorly
Minimum anteroposterior 16 19 19.5 25 34
length of pedicle of neural
arch
Transverse diameter of pedicle 31.5 28 29 27.5 28
of neural arch
Vertical diameter of neural 40 42 42 44 42
canal, anteriorly
Transverse diameter of neural 44 42 38 37 33
canal, anteriorly
Distance between ends of trans- 165 158 154 155 150
verse processes (diapophyses)
Dorsal face of metapophysis to 66 79 85 oi 96
ventral face of centrum,
anteriorly
Tip of neural spine to ventral
face of centrum, anteriorly
Roof of neural arch anteriorly 82 93 93 02 86
to tip of neural spine
Transverse diameter centrum 81 80 84 86 89
posteriorly across demifacets
for capitulum
Vertical diameter of centrum,
posteriorly
163 1161 161
20S oe 32-5 35 37
capitulum at the vertebral end of the rib is lodged in part
in the posterior demifacet on the external face of the pre-
ceding dorsal and in part in the anterior demifacet on the
same face of the centrum of the vertebra to which the
tuberculum is attached. The tuberculum of the rib arti-
culated with the facet at the end of the diapophysis. Behind
the eleventh vertebra, the rib is in contact with an arti-
cular surface on only one dorsal vertebra. The antero-
posterior compression of the neck at the vertebral end of
the rib is terminated on the fifth rib, and an obvious dorso-
ventral compression of the neck commences with the seventh
rib. The internal face of the shaft of the fourth to twentieth
rib is flat, the external at least slightly convex and the width
of each rib exceeds the thickness. Behind the first pair the
ribs progressively increase in length (in a straight line) to
the eleventh or twelfth pair and then decrease; behind
the eleventh pair the distal attenuation of the shaft becomes
more pronounced, and the distance between the articular
face of the capitulum and the tuberculum is shortened.
The lower extremity of each rib is more or less roughened,
presumably for attachment of a ligamentary connection
_ with a costal rib.
While dissecting a male dugong carcass, Owen (1838,
Da D5 DE Dz De Dg D.to Dart D.rz D.rg Dire Dts D.16
4B 2a Oa 5 Sea 59) yer 5 559 5914 58
77 #77 +78 81+ 77+ — 89 88 88+ 90 90
BSE can oe 5 Ome Ott 5505 O55 eee 2
42 42 43 44 46 — 46 41 45 43 42
28 29 628) 638 28 —= 3 3} BG) 24 28
oe) BS) ahs) a) 37 at RII eI ose 9 go BY
Son ob 350) 34: 33 ae 32) S45 SE 33 33
145 137 130 125 123 117 118 114 113 108 111
95 91 95 106 107 — 105 101 105 100 8
155 151 153 162 161 — 166 158 166 159 160
81 81 80 80 80 Gy kB. GS) GFT 79 «882
91 95 95 85+ 874 — 84 86 87 87 84+
37 Co 3S 2 5 5 5 OE OS ict
p. 41) found that the first four pair of ribs had a cartila-
ginous attachment to the sternum; the remainder of the
ribs terminated freely in the mass of abdominal muscles.
In view of the close association of these forty ribs with
the skull, vertebrae and other skeletal elements, one can be
assured that only one individual is represented. Further-
more, the ribs belonging to the right and left sides of the
thorax constitute a consecutive series. Attention is directed
to the disparity in the lengths of the ribs of the first, third,
fifth and sixth pairs, which otherwise appear normal.
The first pair are the shortest of the ribs in the thorax,
the anteroposteriorly compressed vertebral end is abruptly
bent inward, and the transversely flattened distal or sternal
end of the shaft is twisted almost at right angles to the verte-
bral end. There are three processes or facets on the verte-
bral end of the first rib (fig. 37), the knoblike upper one,
the tuberculum, is attached to the end of the diapophysis;
the second, the capitulum, is at the end of a slender neck;
and a third ventral knoblike process may have been con-
nected by ligament with a cervical rib. The first rib of a
skeleton of the dugong (USNM 20861) mounted for display
in the Museum of Natural History has a short piece of a dried
ligament still attached to this lower process. This liga-
88 UNITED STATES NATIONAL MUSEUM BULLETIN 247
ment may have formed a ligamentary connection with the
very rudimentary cervical rib which is loosely articulated
with the seventh cervical on this mounted skeleton. This
cervical rib is bifurcated or at least has two heads; the upper
head articulates with the diapophysis of the seventh cer-
vical, the lower head articulates with the centrum of the
sixth cervical. As regards the occurrence of rudimentary
ribs in certain whalebone whales, Turner (1871, p. 360)
states that the cervical rib possesses neither capitulum nor
neck, nor does it take the place of the ventral transverse
process of the seventh cervical, and it is articulated with
the upper transverse process of this cervical. This lower
process is not developed on the vertebral end of the first
rib of the American manatee (Trichechus manatus latirostris).
The absence of this process on the first rib of the manatee
may bear some relationship to the reduction of the cervicals
to six vertebrae. Depéret and Roman (1920, p. 16, pl. 4,
fig. 6) illustrated the first rib of Felsinotherium serresit and
mentioned the third ventral process below the capitular
facet, but offer no suggestion of its functional significance.
The capitular facet of the first rib articulates with the
anterior demifacet on the external face of the first dorsal
vertebra. On the internal face of the shaft (pl. 42, fig. 6)
is a thick oblique crest extending inward and upward from
the posterior face which may demarcate the area for
insertion of the scalenus muscle.
A much less prominently developed crest can be recog-
nized on the first rib of the dugong. The right and left
first ribs measure respectively in a straight line 250 and 237
mm., and their greatest width (42 mm.) is below the middle
of their length. From the notch behind the tubercular
facet to about the middle of their length, the posterior face
of the shaft can best be described as a crest.
Comparison of the first rib of the Calvert sirenian re-
vealed a rather close resemblance to the first rib of the
Halitherium schinzi (Lepsius, 1882, pp. 138-139, pl. 7, fig.
78) in the general configuration of the vertebral end and
the position of the thick oblique internal crest; this Calvert
rib, however, is otherwise readily distinguished by the
slender shaft and no enlargement of the sternal end. The
similarity of the peculiar configuration of the vertebral end
of this rib is quite close, however, to the first rib of the
dugong. Both possess a slender shaft.
Although somewhat larger, the ribs of the second pair
(pl. 42, fig. 5) have a noticeably thickened shaft. Each rib
is curved from end to end, the sternal end is abruptly
truncated, the area for attachment to the sternum being
markedly reduced, and the vertebral end is turned forward.
An anteroposteriorly compressed neck separates the blunt-
nosed ovoidal capitulum from the low knoblike tuberculum,
the interval between these articular surfaces being 25 mm.
The distal half of the shaft is flattened internally and the
external is convex, though there is an obvious constriction
PART 3
of the proximal third of the shaft. The maximum width
of the shaft is 47 mm. The lengths of the right and left
ribs, respectively, are 308 and 307 mm.
The ribs of the third pair (pl. 42, fig. 4) are more curved
and longer, the right and left measuring respectively 345
and 365 mm. No noticeable constriction of the vertebral
portion of the thick shaft is observable, the maximum
width of the upper portion of the shaft being 45 mm. and
the lower half 47 mm. The external and internal faces of
the shaft are flattened and the attenuation of the lower or
sternal end is abrupt. A less compressed and thicker neck
separates the low flattened tuberculum from the capitulum,
the distance from the capitular articular face to the posterior
edge of the tubercular facet being 65 mm.
The weight of the ribs of the fourth pair (pl. 42, fig. 3)
has increased and the width of the shaft has become more
Figure 37.—First left rib, USNM 16757, of Metaxytherium
calvertense. Abbrs.: c., capitulum; cr., crest of shaft; t.,
tuberculum; v.pr., ventral process.
NEW SPECIES OF EXTINCT MIOCENE SIRENIA 89
uniform from end to end. The lengths of the right and
left ribs are, respectively, 405 and 404mm. At the vertebral
end of the shaft, the neck between the small, low, oval
tuberculum and the enlarged capitulum (24 x 20 mm.)
is thicker than that of the third rib, although the distance
(68 mm.) from the capitular articular face to the posterior
edge of the tuberculum has increased imperceptibly. The
beveling of the attenuated sternal end is quite similar to the
third rib.
The tendency toward flattening of the shaft which is
progressively accentuated toward the posterior end of the
thorax seems to have been initiated with the fifth pair of
ribs (pl. 42, fig. 10). These ribs are larger than the fourth
pair, the right and left ribs measuring respectively 430 and
443 mm., though the end to end curvature of the shaft is
about the same. Both external and internal surfaces are
rather flat, the width of the shaft (maximum, 48 mm.)
changes very little until within 90 mm. of the slightly
attenuated sternal end. At the vertebral end of the shaft,
the tuberculum is a rather large saddle-like depression.
The ribs of the sixth pair (pl. 42, fig. 11) are longer than
the fifth, the right and left measuring, respectively, 443 and
455 mm., the width of the shaft has not changed except
for a more gradual attenuation of the beveled sternal end.
External and internal faces of the shaft are flattened; the
depression external to the tuberculum is more elongated
than on the fifth. An obliquely truncated capitulum is
located at the vertebral end of the bent forward neck, but
the dorsoventral compression of the attenuated neck does
not develop until the seventh rib. The maximum distance
between the articular face of the capitulum and the posterior
edge of the tuberculum is 72 mm.
Backward deflection of the gradually attenuated sternal
end of the shaft becomes more apparent on the seventh
pair of ribs which are slightly wider (maximum width, 54
mm.) than the preceding. The external and internal faces
of the shaft are unmistakably flattened. The inward curva-
ture of the vertebral end of the shaft is accentuated and
the dorsoventrally compressed neck is wider than on the
sixth, though the distance between the capitulum and the
tuberculum has not been altered. The depression external
to the tuberculum, however, is more elongated and some-
what deeper. The lengths of the right and left ribs are,
respectively, 460 and 470 mm.
The length of the right and left ribs of the eighth pair
(pl. 42, fig. 2) are, respectively, 463 and 460 mm. At the
widest point, the breadth of the shaft is 50 mm. and the
attenuation to the truncated sternal end is gradual. There
is a noticeable deflection backward of the sternal end and —
a more abrupt bending inward and forward of the vertebral
end of the curved shaft. The external and internal faces
of the shaft are flattened. The dorsoventrally compressed
goosebeak-like neck diminishes in width from 44 mm. across
the tubercular facet to 24 mm. across the capitular facet.
The elongated depression external to the low tuberculum
is rather deep.
The right and left ribs of the ninth pair measure, respec-
tively, 466 and 470 mm. in astraight line; the maximum
width of the shaft is 51 mm. The attenuation of the sternal
end of the curved shaft is more gradual than on the eighth
and the backward deflection has increased. The neck is
wide and thick, the capitulum is broad and the tuberculum
is a low flattened knob. The distance (68 mm.) between
the posterior edge of the tuberculum and the anterior face
of the capitulum on the vertebral end of the shaft is greater
than on the preceding rib (64 mm.); no increase in the
forward and inward curving of the vertebral end of the
shaft is noticeable.
Of the tenth pair of ribs, the left rib lacks the capitular
end of the neck; these ribs measure 473 and 475 mm. in
length in a straight line. The tenth, eleventh, and twelfth
pairs of ribs are the most massive components of the thorax.
The maximum width (51 mm.) is below the vertebral one-
third of the laterally flattened shaft; below this point the
shaft tapers gradually to the sternal end. The backward
deflection of the sternal end of the attenuated shaft is no
greater than that of the ninth and the forward and inward
curvature of the vertebral end is quite similar. External
to the reduced flattened tuberculum the usual depression
has increased in breadth but decreased in depth. The neck
behind the capitulum is strongly compressed dorsoventrally
and rather gradually attenuated.
Each of the eleventh pair (pl. 42, fig. 1) of ribs, measuring
473 and 475 mm. in length, has thesternal end of the shaft
strongly deflected backward and the vertebral end curved
inward and bent forward. The curved shaft tapers grad-
ually from about the middle of its length (maximum width,
49 mm.) to the small sternal end (18 mm.). The dorso-
ventrally compressed neck between the blunt-nosed capitu-
lum and the low flattened tuberculum resembles the tenth
rib, but the depression external to the tuberculum is reduced
to a deep but rather short (20 mm.) and narrow pit. The
internal face of the curved shaft is more noticeably flattened
than the external face.
The twelfth pair of ribs, measuring 445-++ and 473 mm.,
respectively, in length, are similar in conformation to the
thirteenth pair, except for a larger bluntnosed capitulum at
the vertebral end of the dorsoventrally compressed and
somewhat triangular neck. The neck of the right rib is
broken off and missing. The limits of the flattened tuber-
culum are indistinct. External to the tuberculum is the
usual depression or groove, which is at least four times as
long (23 mm.) as wide and israther deep. The limits of the
flattened tuberculum are indistinct. The curved shaft
tapers from a maximum width of 46 mm. near the middle
of its length to the sternal end and is bent forward and
90 UNITED STATES NATIONAL MUSEUM BULLETIN 247
inward more abruptly at the vertebral end than deflected
backward at the sternal end. It is as uniformly curved
from end to end as the eleventh rib.
Each of the thirteenth pair of ribs, measuring 452 and 460
mm., respectively, in length ina straight line, has an obliquely
truncated capitulum on the end of a short subtriangular
dorsoventrally compressed neck and a relatively low
tuberculum. The depression external to the tuberculum
resembles the groove on the twelfth rib. The tapering of
the shaft toward the distal end is gradual and the backward
deflection of the sternal end as well as the inward curvature
of the vertebral end corresponds with the twelfth rib. The
maximum width of the curved shaft is 44 mm.
The fourteenth pair of ribs, measuring 450 and 445 mm.,
respectively, in a straight line, are curved from end to end;
the shaft of each is deflected backward at the sternal end
and curved inward and forward at the vertebral end. The
shaft gradually tapers from about the middle of its length
(width 43 mm.) to the blunt sternal end (width 16 mm.).
The capitulum at the end of the short subtriangular neck
seems more functionally modified for articulation than the
small flattened tuberculum. A narrow groovelike de-
pression is located external to the tuberculum.
The fifteenth pair of ribs, measuring 435 and 440 mm.,
respectively, in a straight line, are characterized in part by
a more rounded capitulum separated from the low tubercu-
lum by a short, dorsoventrally compressed subtriangular
neck. A shallow elongated groove is present external to
the tuberculum. The sternal or distal third of the curved
shaft is as strongly deflected backward as the fourteenth
rib, and the vertebral end is curved inward, but the neck
is less noticeably bent forward. The shaft is widest (41
mm.) near the end of the proximal or vertebral one-third
and then tapers to the small distal end; the inner face of
the shaft continues to be flattened; the external face is
slightly convex.
The distance from the articular face of the capitulum to
the posterior margin of the tuberculum is 45 mm. on both
the fifteenth and sixteenth ribs. A narrow groove is present
external to the tuberculum. The tuberculum is a low
prominence similar to the facet on the fifteenth rib. The
capitulum remains acuminate and the dorsoventrally com-
pressed neck is subtriangular. The right and left ribs of
the sixteenth pair measure 422 and 424 mm. in length.
The end to end curvature of the shaft is rather uniform,
the distal one-third is deflected backward and the neck bent
forward. A gradual taper of the shaft, commencing below
the vertebral one-third where the maximum width is 41
mm., continues to the small oval distal end.
Except for the shortening of the shaft the general con-
figuration of the seventeenth rib is almost a replica of the
sixteenth rib, the right and left ribs measuring, respectively,
405 and 408 mm. in length. The distal two-thirds of the
PART 3
curved shaft tapers to the small oval end. A similar back-
ward deflection of the distal portion of the shaft exists and
the neck is slightly bent forward. The subtriangular neck
is short but less dorsoventrally compressed and the distance
from the articular face of the capitulum to the posterior
edge of the low knoblike tuberculum is 40 mm. The groove
which is present behind the tuberculum on the preceding
rib has been replaced by a small shallow depression.
Except for the more abrupt taper of the distal 80 mm.
of the shaft and the shortening of the neck, the ribs of the
eighteenth pair (pl. 42, fig. 9) resemble the seventeenth.
The maximum width (43 mm.) of the shaft of the right
rib exceeds the left (38 mm.); the neck of the right rib is
also malformed. The right and left ribs measure, respec-
tively, 382 and 392 mm. in length. The short triangular
neck is not dorsoventrally compressed, the tuberculum is
somewhat protuberant, and the distance from the articular
face of the capitulum to the posterior edge of the tuberculum
is 36 mm. A shallow depression is present external to the
the tuberculum. The vertebral end of the shaft is twisted
slightly and the distal end deflected backward. The inter-
nal face of the shaft is flat and the external convex.
The vertebral ends of both ribs of the nineteenth pair
(pl. 42, fig. 8) appear to be malformed. The right rib
has a very short and broad triangular neck, and an ill-
defined tuberculum. A small acuminate capitulum but no
distinct depression external to the posterior edge of the
tuberculum is present. —The maximum width of the curved
shaft is 40 mm. near the middle of its length; the tapering
of the shaft becomes more gradual beginning 130 mm. above
the small (width 17 mm.) oval distal end. The curvature
of the shaft is accentuated on the vertebral one-third and
the distal end is deflected backward. On the left rib the
vertebral end is markedly compressed dorsoventrally, the
relatively small capitulum is separated from the similarly
reduced tuberculum by a deep notch which reduces the
diameter (12 mm.) of the connecting neck. The right and
left ribs of this pair measure, respectively, 378 and 368 mm.
in length.
Culmination of the progressive shortening of the ribs
behind the twelfth occurs in the twentieth pair (pl. 42,
fig. 7), where the right and left ribs measure, respectively,
343 and 348 mm. in length. At a point about 140 mm.
above the distal extremity the attenuation of the curved
shaft commences, although the taper of the distal 100 mm.
is very gradual; this end is very little if at all deflected
backward beyond the long axis of the shaft. The maximum
width of the shaft is 38 mm. External and anterior to
the small knoblike tuberculum, there is an ill-defined shallow
depression. Between the tuberculum and the small blunt-
nosed capitulum, the short neck is creased obliquely by a
notch or groove.
NEW SPECIES OF EXTINCT MIOCENE SIRENIA 91
THE SOUTH CAROLINA MIOCENE DUGONG
DIOPLOTHERIUM MANIGAULTI Cope
The mammalian fossil specimens obtained during the phos-
phate dredging operations on the Wando, Ashley, and other
rivers in South Carolina unquestionably were derived from
overlying deposits of successive geological ages, seemingly
extending in time from the upper Eocene to the Pleistocene.
Included among such specimens are teeth and cranial
fragments of the upper Eocene archaeocete Dorudon serratus.
Pleistocene land mammals are represented by Megathertum,
Elephas, Equus, Tapirus, Procamelus, Bison, and Castorozdes.
Some, at least, of the varied assortment of beaked whale or
ziphioid rostra, including Choneziphius, Eboroziphius, Dio-
plodon, and Proroziphius, are thought to have been in existence
in Carolina coastal waters in the Miocene, as well as the
shark toothed porpoise Squalodon. Hence proper caution
is required in the appraisal of the age of the sirenian fossils.
The small cranial specimens representing the dorsal por-
tion of the braincase, which Glover Allen (1926, p. 455,
pl. 2, figs. 1-2) identified as Halitherium antiquum (Leidy)
and Simpson (1932a, p. 445) as Halithertum alleni are con-
sidered here to possess features characteristic of either
Felsinothertum or Metaxytherium. At least one cranial roof
(USNM 23394) is sufficiently complete to show that the
nasal bones are separated medially by the forward pro-
jection of the paired frontal bones. The least parietal
width of this specimen is 60mm. The cranial roof (fig. 38)
of this specimen corresponds rather closely in its dimensions
with the skull of the lower Pliocene (Plaisancian) Feélsino-
thertum serresit (Depéret and Roman, 1920, p. 6; fig. 1b; pl.
2, fig. 1b).
Braincase roofs, having similar dimensions and configu-
rations, demonstrate the variable degree of convergence of
temporal crests. Among ten specimens recovered by
dredging the degree of convergence of these crests varies
from wide separation to close approximation on the
longitudinal axis of the paired parietals. These examples
may represent either growth stages or possibly sexual
differentiation.
Associated in the phosphate derived collections with these
small specimens, here referred to Felstnothertum alleni, are por-
tions of skulls of a somewhat larger sirenian. At the request
of Gabriel Manigault, the then director of the Charleston
Museum, Cope (1883, pp. 52-54) described the anterior
symphysial end of a sirenian right premaxillary containing
a large tusk lodged in the alveolus which he named Dio-
plothertum manigaulti. Cope mistakenly asserted that a
second tusk was lodged in the premaxillary external to the
first tusk and that the presence of a second tusk distinguished
‘this form from all other sirenians. A critical examination
of the type specimen from the phosphate beds of the Wando
River northeast of Charleston, S.C., failed to corroborate
this assumption. The overall length of this portion of the
premaxillary (Cope, 1890, pl. 25) is 168 mm., and the bent
downward anterior end is quite broad, the maximum
anteroposterior diameter being 105 mm. Other measure-
ments are: vertical diameter from dorsal face of pre-
maxillary near posterior end of symphysis to ventral
alveolar border, 128 mm.; length of symphysis, 126-- mm.;
length of tusk, 176 mm. (present condition, 153 mm.);
anteroposterior diameter near base, 50 mm.; transverse
diameter, 27 mm. The longitudinal fluting of the tusk is
most pronounced on the internal face.
Cope stated that the premaxillary symphysis of Dzoplo-
therium manigaultt was shorter than that of Rytiodus capgrandi
(Delfortrie, 1880, pl. 6), which was a rather large sirenian,
the complete skeleton measuring 5 meters and the skull
700 mm. The type tusk of R. capgrand: (Lartet, 1866, p.
682) was found in the lower Miocene (Aquitanian) “‘cal-
caire marin coquillier’ at Bournic, near Sos, La Gélise
Valley, Dépt. Lot-et-Garonne, France. The largest of the
two incisor tusks from Bournic in the Laboratoire de
Paléontologie, Museum National d’Histoire Naturelle,
Paris, which is labeled as the type and as having been
Pmx.
5.0r. pr.
Ficure 38.—Cranial roof, USNM 23394, of Felstnotherium alleni.
Abbrs.: Fr., frontal; Na., nasal; Pa., parietal; Pmx., pre-
maxillary; s.or.pr., supraorbital process of frontal.
92 UNITED STATES NATIONAL MUSEUM BULLETIN 247
donated by the Nérac Museum in 1866, measured 260.4
mm. in length and 77.5 mm. in greatest width. The skull
described and figured by Delfortrie was excavated in the
lower Miocene ‘‘marnes sableuse’’ at Saint-Morillon,
Labréde Canton, Dépt. Gironde, France. According to the
measurements published by Delfortrie (1880, p. 143), the
length of the tusk is 300 mm., and the width, 56 mm. No
cheek teeth have as yet been identified as belonging to D.
manigaulti. The length of the roof of the braincase of R.
capgrandi was about the same as that of Metaxythertum
jordani (Kellogg, 1925, p. 66). The premaxillaries of R.
capgrandi were, however, greatly elongated, measuring 450
mm., and the length of the premaxillary symphysis was 240
mm. The zygomatic width of the skull of R. capgrandi was
300 mm., and the width across the supraorbital processes of
the frontals, 240 mm., as contrasted with the corresponding
measurements of 317 and 192 mm., respectively, of M.
jordani. Four cheek teeth (Delfortrie, 1880, pl. 8, fig. 3)
are in place in each maxillary, the molariform series in the
right maxillary being noticeably abraded and those in the
left maxillary strongly abraded on the lingual side and
relatively little worn on the buccal side. These four cheek
teeth are regarded as Pm‘, M', M?, and M’; the length
of the molariform series is 95 mm., and the length of M?*
is 30 mm., and width, 25 mm. The crown pattern of the
Rytiodus cheek teeth does not correspond very closely with
teeth of Metaxytherium.
A left premaxillary (YPM 21334) in the Scanlon collec-
tion of the Peabody Museum of Yale University, which is
broken off about 75 mm. in front of the anterior end of the
mesorostral fossa, also has a large tusk lodged in the
alveolus. The measurements of this rostral fragment are as
follows: overall length, 220 mm.; maximum diameter of
premaxillary about 50 mm., in front of posterior end of
symphysis, 95-+ mm.; transverse diameter of premaxillary
near middle of mesorostral fossa, 32 mm.; maximum
PART 3
diameter of tusk in cross section (presumably about 50 mm.
from base), 51 x 25 mm. Near its commencement the
maximum dorsoventral diameter of the symphysial sutural
contact is 56 mm. on both the type of D. manigaulti and
the Peabody Museum specimen. Both of these pre-
maxillaries have the ventral surface strongly striated or
ridged for reception of the palatal extension of the corre-
sponding maxillary. The bent downward anterior end of
the maxillary, which overlapped the exteroventral surface
of the premaxillary, terminated about 20 mm. in front of
the anterior end of the mesorostral fossa. The estimated
maximum width of the mesorostral fossa is 80 mm. and its
length 150 mm.
Specimens consisting usually of the supraoccipital an-
kylosed to the parietals appear separable into two size
categories. On the largest specimen (YPM 21333), the
width of the supraoccipital is 105 mm. and the least parietal
width is 85 mm. Of those in the smaller size category, the
width of the supraoccipital ranges from 65 mm. to 90 mm.
(USNM 8198), and the least parietal width from 50 mm.
(YPM 21335) to 70 mm. The narrowest braincase has
high, closely approximated temporal crests. The edges of
the supraoccipital are abraded to some extent on all speci-
mens examined.
Two size categories of humeri likewise occur in these
collections. The smaller humeri are as short as 150 mm.
(USNM 23256) and these specimens are characterized in
part by a narrow bicipital groove. The largest humerus
examined measured 210 mm. in length and has a broad
open bicipital groove. Neither of these humeri were
physically mature since the proximal epiphysis was de-
tached and missing on both.
Notwithstanding the uncertainty of age determinations —
of components of mixed assemblages, it is suggested that
the small sirenian should be considered to be Felstnotherium
allent and the large form Metaxythertum manigaultt.
THE COLOMBIA TERTIARY DUGONG
As a gift from the Instituto de la Salle, Bogota, Colombia,
a number of Cretaceous invertebrates and a fragment of a
fossil sirenian skull were presented to Dr. John B. Reeside,
Jr., United States Geological Survey, by Brother Ariste
Joseph in 1923. The mandible of a fossil manatee (Potamo-
stren magdalensis) discovered farther south in the present
Magdalena valley in the Miocene La Venta fauna of the
El Libano sands and clays near Villavieja, Departamento
del Huila, has been described by Reinhart (1951). These
two occurrences demonstrate that during the interval when
the Central American isthmus was submerged pelagic dis-
persal enabled representatives of the Dugongidae and Tri-
chechidae to reach the American region now designated
as Colombia, South America. The occurrence of fossil
vertebrates in the upper Tertiary of the municipality of
Ortega, Dept. Tolima, without an indication of either the
precise locality or the species, has been recorded in the
literature (Botero, 1936, p. 44; Royo y Gomez, 1946, p.
499).
E. D. Ackerman, International Petroleum Company, -
Ltd., has advised that the company’s geologists in Colombia _
report that Ortega as a locality is not sufficiently precise to
permit determination of the specific geologic formation
from which this fossil dugong was derived. He has kindly
furnished the following statement (personal communication):
NEW SPECIES OF EXTINCT MIOCENE SIREINIA 93
“The geologic description ‘gray to green black speckled
sandstone’ suggests the Honda formation, outcrops of
which are present in the general area of Ortega. Palyno-
logic evidence indicates that this unit belongs to the middle
Miocene. Both lithologic and micropaleontologic evidence,
however, suggest the Honda formation to be of continental
origin. Furthermore, Professor R. A. Stirton in his report
to the Servicio Geologico Nacional, Bogota, does not
appear to record marine vertebrates from the Honda.
These data seem to preclude the occurrence of marine
vertebrate fossils in the unit.”
As will be noted in the descriptive portion of the text,
the reduction of the upper cheek teeth row to three molars
would be an unusual accomplishment as early as the lower
Miocene. On the basis of present recorded geologic
occurrences of fossil dugongs this reduction to three upper
molars would logically have been expected in the upper
Miocene.
METAXYTHERIUM ORTEGENSE, new species
Type Specimen: USNM 10870. Adult sirenian. Pal-
atal portion of left maxillary containing M’, M?, and M*.
Collector, Brother Ariste Joseph, August 1920.
Horizon and Locality: Ortega, north of mouth of Rio
Saldana, Departamento Tolima, Colombia. Gray to green
black speckled sandstone; upper Miocene.
Dentition
These three molars (pl. 36, figs. 1-2) are uncrushed and
exceptionally well preserved. Crown wear is minimal; no
cusps have been noticeably reduced by occlusal abrasion.
The length of the maxillary molar series is 80.5 mm. The
molars of the Ortega dugong are larger than those of
Felsinotherium serresi (Depéret and Roman, 1920, p. 12,
pl. 2, fig. 2) and smaller than those of Felsinothertum gastaldi
(Zigno, 1878, p. 946, pl. 4). The first and second upper
molars of F. serresii are more subquadrangular than the
same molars of the Ortega sirenian; the placement of the
cusps, however, is quite similar, but the anterior lake be-
tween the cingulum and the paracone on the Montpellier
molars is very narrow. M* on the Gennevaux specimen of
F. serresit seems not fully erupted. The worn left M® on
the skull (Depéret and Roman, 1920, pl. 2, fig. 1d) in the
Hortolés collection is less elongated, though the arrange-
ment of the cusps on the crown is not materially different.
Lengths of the molar teeth on the right and left maxillaries
of the specimen in the Gennevaux collection, Université
de Lyon, published by Depéret and Roman (1920, p. 12)
are as follows: M'!, 18mm.; M?, 21 mm.; M?’, 22 mm.
On the buccal side two separated roots are visible for
M!, M?, and M®; on the lingual side M? has a single root
' and the other two molars appear to have two roots.
210-301—66——3
Each of these molars has the anterior half of the crown
separated from the posterior half by a deep transverse
valley which is only slightly obstructed by the metaconule.
An obvious indentation on the buccal side of the crown
of M! marks the external end of the deep, narrow transverse
valley. The front portion of the crown is truncated oblique-
ly anteriorly from buccal to lingual side. This first molar
has the enlarged paracone connected with the anterior
faintly cuspidate cingulum by a short cuspule and is con-
tinuous medially with the small protoconule which in
turn is not cut off from the crescentric rim of the lingual
protocone. A deep transverse lake intervenes between the
anterior crest of the cingulum and the continuous enamel
connecting isthmus or forward wall of the paracone, proto-
conule and protocone occlusal surface. The anterobuccal
rounded angle of the crown projects beyond the level of
the metacone. On the hinder half of the crown of M!, a
thin cleft separates the metacone from the centrally placed
metaconule; the occlusal surface of the latter is, however,
continuous with that of the obliquely worn anterior face
of the hypocone. A deep triangular lake intervenes between
the buccal metacone, the lingual hypocone, and the rather
thick liplike posterior cingulum. Measurements of M’ are
as follows: width across protocone, 19.5 mm.; width across
hypocone, 17.5 mm.; length, 22 mm.
M2 is longer (length, 26 mm.) and wider than M1;
the portion of the enamel crown in front of the deep
transverse valley is larger than the posterior portion, the
width across the protocone being 23 mm. and across the
hypocone 21.2 mm. On the buccal side a thin cleft
separates the paracone from the antero-external parastyle,
which in turn is separated in similar manner from the rather
broad anterior cingulum. The large protoconule is wedged
in between the more elevated and less abraded paracone
and the protocone. The deep anterior lake between these
three cusps and the anterior cingulum is relatively small.
The metaconule is likewise wedged in between the buccal
metacone and the hypocone. On the buccal and lingual
sides of the posterior cingulum there is a low blunt-edged
cuspule. These cuspules constitute the posterolateral
borders of the hexagonal lake and are separated by a cleft
from the metacone and hypocone, respectively.
M® is the largest and longest of the three maxillary
cheek teeth. Measurements of the enamel crown are as
follows: width across protocone, 25 mm.; width across
hypocone, 21 mm.; length, 29.5 mm.; length-width ratio,
1.18. The paracone is slightly smaller than the protocone;
its apex, however, is elevated above the centrally placed
protoconule and the protocone. The dimensions of the
anterobuccal parastyle are comparable to those of this
cusp on M? and this style is likewise separated from the
rather broad anterior cingulum by a thin cleft. On the
lingual side the cingulum has an enlargement whose
94 UNITED STATES NATIONAL MUSEUM BULLETIN 247 PART 3
dimensions are the same if not larger than those of the
parastyle. The quadrangular anterior lake is larger than
that of M?.
The deep transverse valley is deflected slightly forward
centrally by the more forward placement of the rather
large median posterior cusp (metaconule). The unworn
apices of the metacone and hypocone are not elevated
above the metaconule; the hypocone is, however, pressed
more closely against the metaconule than is the metacone.
In contrast to M? there are three distinct cuspules on the
posterior cingulum; the apices of the buccal and lingual
cuspule are, however, elevated above the smaller medial
cuspule. The buccal and lingual cuspules are also separated
from the metacone and hypocone respectively by a thin
cleft. The lake in front of the posterior cingulum is smaller
than that of M?.
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1934. Beitrage zur Kenntnis Tertidrer Sirenen, I: Die Eozainen Sirenen des Mittelmeerge-
bietes; II: Die Sirenen des Belgischen Tertiars. Mem. Mus. Roy. Hist. Nat. Belgique,
no. 63, pp. 352, 16 figs., 11 pls. Dec. 31, 1934.
98
UNITED STATES NATIONAL MUSEUM BULLETIN 247
Smpson, GEORGE GAYLORD
1932a. Fossil Sirenia of Florida and the evolution of the Sirenia. Bull. American Mus.
Nat. Hist. New York, vol. 59, pp. 419-503, 23 figs. Sept. 6, 1932.
1932b. Mounted skeletons of Eohippus, Merychippus and Hesperosiren. American Mus. Novi-
tates, no» 587, pp. l—/— Decxlolos2
SPILLMANN, FRANZ
1959. Die Sirenen aus dem Oligozan des Linzer Beckens (ober Osterreich), mit Ausfiihrungen
iiber Osteosklerose” und ‘‘Pachyostose.”’ Denkschr. Osterr. Akad. Wissensch. math.-
naturwiss. K]., Wien, vol. 110, pt. 3, pp. 1-68, 34 figs., 4 pls.
STuDER, THEOPHIL
1887. Ueber den Steinkern des Gehirnraumes einer Sirenoide aus dem Muschelsandstein
von Wiirenlos (Kt. Aargau), nebst Bemerkungen iiber die Gattung Halianassa H.
v. Meyer und die Bildung des Muschelsandsteins. Abhandl. Schweizerischen pala-
ontol. Gesellschaft, Zurich, vol. 14, pp. 3-20, 2 pls.
Tuomas, OLDFIELD, AND LYDEKKER, RICHARD
1897. On the number of grinding teeth possessed by the manatees. Proc. Zool. Soc. London
for 1897, pt. 3, pp. 595-600, pl. 36. Oct. 1, 1897.
TurRNER, WILLIAM
1871. On the so-called two-headed ribs in whales and in man. Journ. Anat. and Physiol.,
vol. 5, pp. 348-362.
ZIGNO, ACHILLE DE
1878. Sopra un nuovo sirenio fossile scoperto nelle colline di Bra in Piemonte. Atti R. Accad.
Lincei, Mem. Classe Sci. Fis. Matem. e Nat., Roma, ser. 3, vol. 2, pp. 939-949, 6 pls.
PART 3
4. A New Odontocete From the Calvert
Miocene of Maryland
i FEBRUARY 1965, Howard W. Hruschka while search-
ing for fossil bones along the Chesapeake Bay shore
north of Governors Run, Md., found the mandibles here-
inafter described. ‘They were near the tide level in a mass
of marl which had been dislodged from the face of the cliff
during a previous storm. These mandibles belonged to a
toothed cetacean somewhat larger than any of the pre-
viously recorded Calvert odontocetes that are characterized
by an elongated rostrum. Mr. Hruschka generously pre-
sented the specimen to the United States National Museum.
HADRODELPHIS, new genus
Type species: Hadrodelphis calvertense, new species.
Diagnosis: Mandibles thick, robust, ankylosed anteriorly
by symphysial fusion; mandibular alveoli large, antero-
posterior diameter 18-23 mm., separated by 5-8 mm.
septa or interspaces; mandibular teeth with black enamel
crowns; crowns of posterior teeth with anastomosing fine
striae and with apical portion of subconical crown bent
inward, overhanging broad internal basal shelf; enamel
crown of more anterior mandibular teeth nearly conical
and with internal shelf progressively reduced.
Type specimen: USNM 23408. Portion of right man-
dible ankylosed anteriorly to a shorter portion of the left
mandible at symphysis. Collector, Howard W. Hruschka,
February 13, 1965.
Horizon and Locality: Marl in a fall at base of cliff, 900
feet north of road end at Governors Run, Calvert Co., Md.
Calvert formation, middle Miocene.
Teeth
The incomplete right mandible (length, 388 mm.) has
five teeth (pl. 44, fig. 1) with crowns in situ, 1 root only
and 7 empty alveoli. The shorter portion (length, 233
mm.) of the left mandible has two teeth with worn crowns
in situ and 4 empty alveoli. In the symphysis of these
mandibles the alveoli are larger than those at the posterior
broken end of the right ramus which suggests that the
lower teeth were progressively slightly diminished in size
toward the posterior end of this tooth row. In the right
mandible (pl. 45, fig. 1) the five posterior alveoli with teeth
in situ occupy an interval of 120 mm. The five anterior
alveoli with complete rims in the right mandible occupy an
interval of 140mm. The largest alveolus in the symphysial
portion of the left mandible measures anteroposteriorly 23
mm. at the rim and the smallest posterior alveolus in the
right mandible 18.5 mm. The walls of the alveoli are not
quite vertical, although the backward slope is not very
pronounced. Judging from the dimensions of the alveoli,
the anterior teeth were slightly larger than those at or
near the posterior end of the tooth row.
The fourth tooth (pl. 45, fig. 2) in front of the broken
posterior end of the right mandible (tenth tooth behind
broken anterior end) was removed from its alveolus for
examination and illustration. No appreciable variation in
the configuration of the enamel crown of the five posterior
teeth in the right mandible is noticeable. The apex of the
subconical crown curves inward, overhanging the broad
internal basal shelf. The black enamel on the crown of
these posterior teeth is lightly roughened with irregular
and anastomosing fine striae which are almost impercepti-
ble except under magnification. No cingulum is developed.
There is no distinct neck below the enamel crown, although
the rounded ventral rim is pinched-in or turned inward.
The internal basal shelf is progressively diminished toward
the anterior end of the tooth row and is barely visible on
the posteriormost of the two teeth retained in the left
mandible. The conical apices of these two teeth are worn
down transversely, The basal margin of the enamel
crown seems to extend ventrally farther on the internal
face than on the external face, although the distance from the
conical apex to the ventral rim is approximately the same
on both faces. None of the teeth possess any vestige of
99
100
accessory cusps or tubercles nor an anterior or posterior
cutting edge (carina). The teeth preserved in the two
mandibles show no evidence of lateral occlusal wear.
The root of the extracted mandibular tooth (pl. 45,
fig. 3) is widest near the middle of its length, bent back-
ward distally, and compressed from side to side on the
distal one third. The extremity of the root is rugose,
with at least six tubercles; the pulp cavity is closed at the
extremity. Accidental breakage of the root revealed the
existence internally of an open pulp cavity. These mandib-
ular teeth are larger and have relatively lower crowns
than those of Lophocetus pappus (Kellogg, 1955, p. 120).
Measurements of the tooth (in mm.) are as follows:
Greatest length 52
Least length of root 38
Greatest anteroposterior diameter of root 14
Greatest transverse diameter of root 16
Greatest height of crown 13
Greatest anteroposterior diameter of crown at base 10
Greatest transverse diameter of crown at base 12
Mandibles
The posterior portions of both mandibles are broken off;
the right ramus is more complete than the left. The ante-
rior extremities of both mandibles (pl. 44, fig. 1) are also
missing. Both mandibles are firmly ankylosed at their
broken-off anterior ends. In their present condition they
diverge behind this symphysial union, but, for a distance
of 80 mm. anterior to the commencement of the outward
curvature, the internal surface of each ramus is straight.
This may indicate a more posterior extension of the sym-
physis. The posterior portion of the right ramus exceeds
55 mm. in depth anterior to the missing coronoid process,
and anteriorly the vertical diameter of the symphysis be-
comes less than 39 mm. The symphysial portion of the
ankylosed rami also tapers toward the anterior extremity,
the transverse diameter becoming less than 45 mm. The
opposite alveoli are rather closely approximated in the
symphysial region and the narrowed dorsal surface of the
symphysis between these opposite teeth rows is relatively
smooth and flat. No pits for the reception of the apices of
the teeth in the rostrum are present.
Dorsoventral diameter of ankylosed symphysis at broken
anterior end, 39 mm.; dorsoventral diameter of symphysis
at level of fourth alveolus counting backward from anterior
end, 46 mm.
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 4
The outer surface of the right mandible is nearly vertical
near the broken-off posterior end and anteriorly becomes
more convex and gradually shifts to a more oblique slope
from the alveolar edge to the midline ventrally. Seven
external mental foramina (pl. 44, fig. 2) are present on the
preserved portion of the right mandibular ramus. The
two posteriorly located foramina are the largest of these
seven; the hindermost one opens into a backward extend-
ing groove, but the larger foramen 33 mm. in front of it is
not associated with a groove. The five smaller anterior
foramina open into anteriorly directed grooves varying in
length from 10 to60 mm. The mandibular rami are rather
thick and sturdy. At the posterior broken end of the right
ramus, the internal mandibular canal measures 32 mm.
vertically and 15 mm. transversely.
From Macrodelphinus kelloggi (Wilson, 1935, p. 28), exca-
vated in the middle Miocene Pyramid Hill sand, Kern
Co., Calif., this Calvert odontocete is distinguished readily
by considerably fewer and larger teeth, much larger and
more widely spaced alveoli, as well as thicker and more
robust mandibular rami.
Although the rostrum has not as yet been recorded, the
width of the mandibular symphysis of the Florida middle
Miocene genus, Megalodelphis magnidens (Kellogg, 1944, p.
445), indicates a skull of somewhat larger dimensions,
particularly the width of the rostrum, than the Calvert
Miocene odontocete. The transverse diameter (60 mm.)
of the combined rami (USNM 23408) at the level of the
posterior end of the symphysis is not more than 27 percent
of the corresponding measurement of the symphysis of the
Florida The antero-
posterior diameter (18-20 mm.) of alveoli located posterior
to the symphysis (USNM 23408) is slightly smaller than
the corresponding alveoli (23-25 mm.) of Megalodelphis
magnidens (MCZ 17883) and the interspaces or septa (5-8
mm.) between the alveoli are much narrower than those
(10-12 mm.) of magnidens.
The rostral fragment which constitutes the type of
Champsodelphis valenciennesii (see Kellogg, 1944, pp. 448, 449,
451) from the Helvetian shell marl at Sort, 8 kilometers
from Dax, Département Landes, France, should correspond
in general configuration and dimensions to the missing
rostrum of this Calvert odontocete. It is obvious that the
teeth of this Helvetianspeciesrepresent a somewhat different
type of dentition. The Helvetian species valenciennesii,
however, does not belong in the genus Champsodelphis.
Hawthorn formation odontocete.
A NEW CALVERT MIOCENE ODONTOCETE 101
BIBLIOGRAPHY
KELLOGG, REMINGTON
1944. Fossil cetaceans from the Florida Tertiary. Bull. Mus. Comp. Zool. Harvard Coll.,
vol. 94, no. 9, pp. 433-471, 10 figs., 6 pls. November 1944.
1955. Three Miocene porpoises from the Calvert Cliffs, Maryland. Proc. U.S. Nat. Mus.,
vol. 105, no. 3354, pp. 101-154, 1 fig., 21 pls. Dec. 14, 1955.
Witson, LEsuik E.
1935. Miocene marine mammals from the Bakersfield region, California. Bull. Peabody Mus.
Nat. Hist., Yale Univ., no. 4, 143 pp., 23 figs. Sept. 9, 1935.
210-301—66——4
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U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 33
SKULL, USNM 16757, METAXYTHERIUM CALVERTENSE
1, Dorsal view; 2, lateral view.
U.S. NATIONAL MUSEUM
SKULL, USNM 16757, METAXYTHERIUM CALVERTENSE
1, Ventral view; 2, right maxillary cheek teeth.
BULLETIN 247, PLATE 34
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 35
METAXYTHERIUM CALVERTENSE
Teeth: 1, right upper third molar (USNM 234009); 2, right upper third molar (USNM 16757); 3, left upper third molar (USNM 23281);
4, left lower second molar (USNM 23271); 5, left posterior molar milk tooth (USNM 16630); 6, right posterior molar milk tooth
(USNM 16630); 7, left penultimate lower cheek tooth (USNM 16630); 8, right penultimate and posterior lower cheek teeth USNM
16620). Ear bones, USNM 16757: 9, Right tympanic half ring; 10, left incus.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 36
Left maxillary cheek teeth, USNM 10870, of Felsinotherium ortegense: 1, ammonium chloride treated; 2, not treated.
Right periotic, incus and stapes, USNM 16757, of Metaxvtherium calvertense: 3, posttympanic process of squamosal removed.
BULLETIN 247, PLATE 37
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U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 43
SCAPULAE AND CHEEK TEETH
Metaxytherium calvertense: 1, right scapula, external view (USNM 16757); 2, left scapula, external view (USNM 16630).
Halianassa studeri: 3, left maxillary cheek teeth (type, Studer, 1887, pl. 1, fig. 4).
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 44
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U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 45
POSTERIOR MANDIBULAR TEETH, USNM 23408, HADRODELPHIS CALVERTENSE
1, Internal view of posterior teeth, right mandible; 2, anterior view of posterior tooth; 3, internal view of posterior tooth.
UNITED STATES NATIONAL MUSEUM BULLETIN 247
FOSSIL MARINE MAMMALS
From the Miocene Calvert Formation
of Maryland and Virginia
Parts 5-8 (end of volume)
REMINGTON KELLOGG
Research Associate, Smithsonian Institution
MUSEUM OF INGA UR Awe HISTORY
SMITHSONIAN INSTITUTION - WASHINGTON, D.C. - 1968
For sale by the Superintendent of Documents, U.S. Ge
t Er
5. Miocene Calvert Mysticetes Described
by Cope
6. A Hitherto Unrecognized Calvert
Cetothere
7. A Sharp-nosed Cetothere From the
Miocene Calvert
8. Supplement to Description of PARIETO-
BALAENA PALMERI
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5. Miocene Calvert Mysticetes Described by Cope
ETHODS OF COLLECTING and preserving fossil cetacean
M remains were less than satisfactory during the past
century. Inexperienced or untrained persons were pick-
ing up at waters edge bones from the fallen debris of the
marine formations exposed along the western shore of the
Chesapeake Bay, the Patuxent River, and the cliffs on the
Potomac River. The novelty and supposed rarity of such
finds seemingly influenced Leidy and Cope to seek the assist-
ance of workers in marl pits and helpers on farms in the re-
covery of all such curiosities. Broken and otherwise imperfect
vertebrae and mandibles of fossil cetaceans received from
such sources were the usual kind of accessions to museum
collections. Such inadequate and often nondiagnostic
specimens became the basis for generic and specific names.
With few exceptions these species were based on skeletal
elements other than portions of skulls. In view of present
knowledge based on more complete skeletal materials, the
proposal during the past century of generic and specific
names for imperfect, nonassociated vertebrae and portions
of mandibles may be attributed, in part, to unawareness of
the probable extent of individual variation and growth
changes. Except in a rather few instances determinable
comparisons with type specimens of this nature have not
been rewarding. Although a conscientious effort has con-
sistently been made during the past forty years to identify
or associate Cope’s cetacean types with more completely
preserved specimens, this has so far proven impractical for
several of his fossil mysticetes.
Since Winge (1909) concluded that the upper Miocene
(Anversien) Mesocetus Van Beneden was equivalent to the
lower Pliocene (Diestien) Plestocetus Van Beneden, and that
Metopocetus Cope was probably also equivalent thereto,
consideration should be given to the availability of this
generic name for a particular kind of fossil mysticete. As
regards Mesocetus, True (1912) concurred with Winge,
but thought that Metopocetus was questionably valid.
Three species, hupschii, burtinii, and garopit, based on
skeletal materials from the Diestien “‘sables’ (lower
Pliocene) at Saint Nicolas, Belgium, in the Musée de
Université Catholique, Louvain, were included when the
generic name Plesiocetus was established by Van Beneden
(1859, p. 139). Some twelve years later Van Beneden
(1872, p. 15) decided to restrict the application of the generic
name Plesiocetus to P. garopiit, a large species very near the
living Balaenoptera. In this article, Plesiocetus hupschii and
P. burtini were referred to Cetotherium Brandt and two
additional fossil mysticetes Cetotherium brevifrons and C.
dubium were described.
After having had his attention directed by Brandt to the
elongated lumbars and the absence of capitular articulation !
with the centrum by anterior as well as posterior ribs of
related mysticetes, Van Beneden (1882, p. 59), in September
1872, was not quite so certain of the generic distinctness
of Plesiocetus garopit.
Van Beneden and Gervais (1874-1880, p. 273) state that
recognition of the genus Plesiocetus was based on notable
differences that exist in the bones of the skull, particularly
the tympanic bulla and the cervical vertebrae as con-
trasted with others. Four species, Plesiocetus garopi (Van
Beneden and Gervais, 1874-1880, pl. 16, figs. 1-9), P.
burtini, P. hupschi, and P. gervaisiz, were recognized. In
his revised diagnosis, Van Beneden (1880, p. 17) stated
that Plestocetus was nearest to the living balaenopterines,
that the articular condyle of the mandible was round
1 The second, third, and fourth pair of ribs of Balaenoptera (Sibbaldus)
musculus, B. physalus, B. borealis, and B. acutorostrata have the tuber-
culum separated from the capitulum by a well-defined neck, although
the capitulum seemingly does not articulate with the centrum of a
dorsal vertebra. As regards the Calvert Miocene cetotheres, the
capitulum on each of the seven or eight anterior pairs of ribs artic-
ulates in a definite demifacet on the posteroexternal surface of the
centrum of the preceding vertebra.
103
104
(like the head of the humerus) similar to that of true balae-
nids, that the tympanic bulla was distinctive, and that
especially great importance was attached to the distance
between the (supra) occipital and the nasals which de-
termined more or less the length of the skull. The species
of Plesiocetus recognized by Van Beneden were, brialmontii,
dubius, hupschit, and burtinii. No mention of Plesiocetus
garopii is made in Van Beneden’s final review (Van Beneden,
1885) of the genus Plestocetus. Omission of P. garopii seems
to imply that Van Beneden no longer accepted as valid
the characteristics he previously assigned to this species,
but regrettably he failed to comment on its actual relation-
ships. The type species of Plesiocetus has been fixed (Kellogg,
1925, p. 51) as P. hupschit.
Diagnostic portions of skulls, if in existence, have neither
been described nor illustrated by Van Beneden (1885) for
Plesiocetus brialmontit, P. dubius, or P. burtinit. The tympanic
bullae assigned to P. brialmontit (Van Beneden, 1885, pl. 2)
and to P. dubius (op. cit., 1885, pl. 14) are balaenopterine.
The condyle of the mandible (op. cit., 1885, pl. 22, fig. 9)
and the periotic (op. cit., 1885, pl. 21, figs. 2-7) of the
referred specimen of P. hupschit are also balaenopterine.
These species were rather large mysticetes, the length of
the humerus as illustrated is 300 mm. for P. hupschit (Van
Beneden, 1885, pl. 24, figs. 2-3), 315 mm. for P. dubius
(op. cit., 1885, pl. 15, fig. 6), and 350 mm. for P. brial-
montii (op. cit., 1885, pl. 4, fig. 1). The length of the radius
of P. hupschii (op. cit., 1885, pl. 25, figs. 4-5) is 435 mm.,
of P. dubius (op. cit., 1885, pl. 16, fig. 3) 475 mm., and of
P. brialmontit (op. cit., 1885, pl. 5, fig. 3) 510 mm. These
skeletal details do not indicate a close relationship of these
Belgian species with the Calvert Miocene genera which
were discussed by Winge (1909) and True (1912).
Uncertainties in the allocation of isolated bones uncovered
during excavation to any one of several related species
must always be considered. Reference to the dispersal
of bones in the sediments of the Antwerp basin has been
made by Van Beneden (1886, p. 34). Furthermore, the
sequence of the catalog numbers assigned to skeletal ele-
ments of the above-mentioned four species does not lend
creditability to the accuracy of such attributions. Sufficient
diagnostic criteria for the recognition of Plesiocetus as a
valid genus are not presently known.
Winge (1909, p. 25) thought that Siphonocetus Cope was
probably equivalent to Cetotherium Brandt, while True
(1912, p. 3) regarded this opinion as doubtful. An upper
and lower aqueduct shown in the cross section of the
mandible of Cetotherium rathkii illustrated by Brandt (1873,
pl. 1, fig. 9) lead Winge to conclude that this division of
the internal mandibular canal was not different from that
described by Cope for Siphonocetus priscus (Leidy).
It has not been feasible to identify the type mandibular
fragment of Siphonocetus priscus with mandibles associated
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 5
with Calvert Miocene skulls. The architecture of the skull
of Cetotherium rathkit is quite unlike that of any of the North
American species of fossil mysticetes, with the possible
exception of Cetotherium furlongi (Kellogg, 1925, fig. 1). The
overriding of the central interorbital region by the posterior
ends of the rostral bones (ascending processes of the pre-
maxillaries and maxillaries and the nasals) on the skull of
Cetotherium rathkii (Brandt, 1873, pl. 1, fig. 1) is decidedly
more pronounced than on skulls referred to Parietobalaena
palmeri. The location on this Sarmatian cetothere skull of
the nasal bones entirely behind the level of the preorbital
angles of the supraorbital processes of the frontals, as well
as the unusually narrow and presumably strongly attenuated
rostrum, are quite different. The genus Cetotherium un-
questionably represents a more advanced stage in the
general process of modification of the mysticete skull by
telescoping.
A more detailed discussion of each of Cope’s Calvert
Miocene mysticetes follows.
For permission to study specimens in their respective
collections, I am indebted as follows: the type of Mesocetus
stphunculus Cope to Dr. Walter Granger, The American
Museum of Natural History (AMNH) in New York City;
the types of Balaena prisca Leidy, Megaptera expansa Cope,
Eschrichtius pusillus Cope, and Eschrichtius cephalus Cope, to
Dr. Horace G. Richards of the Academy of Natural Sciences
of Philadelphia (ANSP); the types of Tretulias buccatus
Cope, Ulias moratus Cope, Metopocetus durinasus Cope,
Balaenoptera sursiplana Cope, and Partetobalaena palmeri
Kellogg to Dr. C. Lewis Gazin of the United States National
Museum (USNM) in Washington, D.C.; and the mysticete
types from the Antwerp basin described by Van Beneden to
Dr. Victor Van Straelen, Director, Musée royal d’Histoire
naturelle in Brussels (MNHB), Belgium. Through continued
assistance of the late Sydney Prentice, line drawings were
prepared some twenty years ago for the Miocene specimens
here illustrated, as well as those in part one of this bulletin.
Assistance in the preparation of illustrations was also
received from Lawrence B. Isham. These illustrations as
well as the outline drawings included in this part are true
projections made with a pantograph.
ESCHRICHTIUS Gray
Eschrichtius Gray, 1864, Ann, & Mag. Nat. Hist., London, ser. 3
vol. 14, no. 83, p. 350.
Type Species: Megaptera? robusta = Balaenoptera robusta
Lilljeborg, 1861, Féredrag vid Naturforskaremétet i
Képenhamm, 1860, p. 602.
Type Specimen: Right and left mandibles, stylohyal,
atlas and 3 cervicals, 7 dorsals, 8 lumbars, 14 caudals, 4
chevrons, 22 ribs, sternum, right scapula, left humerus,
right radius and ulna, 6 carpals, 4 metacarpals, and 4
phalanges. Mineralogisk-geologiska institut, Kungliga Uni-
MIOCENE CALVERT MYSTICETES
versitetet i Uppsala, Sweden. Collectors, Dr. J. O. von
Friesen, F. M. von Friesen, and W. Lilljeborg; 1859.
Type Locality: Skeleton dug up on Grasé (Grassisle) in
Roslagen, Upland, Sweden.
Diagnosis: This genus was established by Gray for the
sub-Recent Balaenoptera robusta Lilljeborg. Gray (1866, p.
132, fig. 21) published line drawings forwarded to him by
Lilljeborg of a cervical vertebra, mandible, scapula, and
sternum of this whale. Gray’s generic diagnosis directed
attention to the scapula with a distinct acromion and
coracoid process, mandible with a low, but little developed
coronoid process, and a cervical vertebra with the neural
canal broad in comparison with the centrum. This genus
was regarded by Gray as a close relative of Megaptera
(the humpback). The discovery in Holland of skulls,
mandible, periotics, axis, scapula, humerus, radius, and
ulna enabled Van Deinse and Junge (1937) to demonstrate
that the Recent gray whale now restricted to the North
Pacific Ocean was present at that time in the North Atlantic
Ocean. Cope’s articles published during this decade
provide no evidence that he had consulted the British
Museum catalog of seals and whales (Gray, 1866) and
seemingly he was not aware of the characteristic shape of
the Eschrichtius mandible whose vertical diameter in front
of the coronoid process is not appreciably greater than near
the anterior end. Otherwise, considering his usual perspi-
cacity, it is difficult to explain the initial application of the
generic term Eschrichtius to a large Calvert mysticete (Cope,
1868a, p. 131). The skeletal parts of Eschrichtius cephalus
Cope (Cope, 1868a, p. 148; type, ANSP 12691, 12692,
12941) included both mandibles and four cervical vertebrae,
but no scapulae. Both of these mandibles are elongated
and markedly attenuated toward the anterior end, but on
both the coronoid process is broken off and the condyles
are missing. The configuration of these Calvert mandibles
is quite close to that of a young Balaenoptera physalus
(USNM 16039).
Cope (1868b, p. 147) observed later that Eschrichtius differs
in part technically from Megaptera in the presence of an
acromion on the scapula, but since this skeletal element is
not represented among his fossil materials, he relied on the
“sreat size of the neural canal as compared with the
vertebral centra” in describing a second cervical vertebra
without epiphyses from eastern Virginia as Eschrichtius
leptocentrus (type, ANSP 12693).
ESCHRICHTIUS CEPHALUS Cope
Eschrichtius cephalus Cope, 1868a,b, Proc. Acad. Nat. Sci. Phil-
adelphia, vol. 19, pp. 131, 144, 148.
Cetotherium cephalus Cope, 1890, American Nat., vol. 24, no. 283,
pp. 612-615, figs. 7, 8, pl. 22.
Type Specimen: ANSP 12691. Right and left mandibles
with hinder ends destroyed behind level of coronoid proc-
105
esses, both premaxillary bones incomplete, a portion of the
maxillary, a portion of the vomerine trough, portions of
both squamosals, left humerus, left radius, two carpals, and
one phalange. Collector, James T. Thomas; October 27,
1867.
Fourth, fifth, sixth, and seventh cervical vertebrae.
ANSP 12692. Collector, James T. Thomas; October 27,
1867.
One half of the atlas, 3 lumbar vertebrae, and 2 caudal
vertebrae. ANSP 12941. Collector, James T. Thomas;
October 27, 1867.
Type locality: In the bed and opposite bank of a small
run, not far from the home of James T. Thomas, near the
Patuxent River, about one mile east of site marked Patuxen
(U.S.G.S. Brandywine sheet), 2 miles east of Hughesville,
Charles County, Maryland. Calvert formation, middle
Miocene.
Referred Specimens: (1) AMNH 9846: right tympanic
bulla; no locality data. (2) AMNH 1750: left periotic;
(?) Yorktown, Va., Yorktown formation, upper Miocene.
(3) USNM 23749; right ulna, incomplete; coll. Thomas
G. Gibson, April 1963; National Military Park, Petersburg,
Prince George Co., Va., Calvert formation, middle Miocene.
Diagnosis: In the fall of 1867, Cope accepted an invita-
tion to visit the home of Oliver N. Bryan at Marshall Hall
Charles County, Maryland. With Bryan, Cope examined
exposures of the Miocene formations in southern Maryland
between the Patuxent and Potomac Rivers. From an old
man, James T. Thomas, living near the Patuxent River,
Cope on October 27, 1867 (Osborn, 1931, p. 148) obtained
two mandibles seven feet in length, portions of the pre-
maxillary and other pieces of the skull, four cervical verte-
brae, a humerus, a radius, 2 carpals, and one phalange of a
large mysticete, which he subsequently named Eschrichtius
cephalus. Included with these skeletal elements were one
half of the atlas, 3 lumbar and 2 caudal vertebrae. This
specimen now is the property of the Academy of Natural
Sciences of Philadelphia. One year later, Cope (1868d,
p. 184) stated that this specimen was found in the bed and
opposite bank of a small run near the Thomas residence,
which was located about one mile east of Patuxent, near
Hughesville, Charles County, Maryland.
From these few remains Cope (1890, pl. 22) attempted a
restoration of the skeleton. Other skeletal material collected
during the past ten years shows that this reconstruction is
remarkably accurate when one considers the scanty evidence
on which it was based. Cope estimated that the length of
the skeleton of this mysticete was about 31 feet and that the
skull comprised about one-third of the total length.
Cope was impressed by the great length of the mandible
as compared with the length of the cervical series. This
condition exists, however, in most of the Recent whalebone
whales. Cope seemingly overlooked the fact that the depth
106 UNITED STATES NATIONAL MUSEUM BULLETIN 247
of the mandibular ramus in front of the coronoid process
as compared with the anterior end is relatively greater
than has been noted for any other Calvert mysticete and
that it bears a much closer resemblance to the mandible
of a young Balaenoptera physalus (USNM 16039) than to any
known cetothere.
W))))) ~S
PART 6
It may appear illogical to conclude in the absence of the
precise details of construction of the braincase and of the
condyle of the mandible that cephalus is referable to an
existing genus. Nevertheless, the portions of the skeleton |
herein described indicate a close affinity if not identity with |
Balaenoptera.
Ficure 39.—Views of left periotic, AMNH 1750 of (?)Balaenoptera sursiplana Cope: a, ventral or tympanic view; 4, internal or cerebral
view. Abbrs.: a.i.c.F., internal aperture of aquaeductus Fallopii; aq.F., epitympanic orifice of aquaeductus Fallopii; a.v., aperture
of aquaeductus vestibuli; c.f., channel for facial nerve; f.a.s., fossa for extension of air sac system; f.c.m., fossa for head of mallus;
fe.o., fenestra ovalis; fe.r., fenestra rotunda; f.st., fossa for insertion of stapedial muscle; m.a.i., internal acoustic meatus; p.c., pars
cochlearis; pr.a., anterior process or pro-otic; pr.p., posterior process or opisthotic; t.s.f., tractus spiralis foraminosus.
MIOCENE CALVERT MYSTICETES
Skull
Cope does not state whether the rostrum was complete
when it was found. If the skull (ANSP 12691) was fairly
complete, it must have been largely destroyed during exca-
vation, for all that exists today is the incomplete right and
left premaxillary bones, a portion of the maxillary, a section
of the vomerine trough, and portions of both squamosals.
Measurements (in mm.) of portions of skull, ANSP 12691,
are as follows:
Premaxillary, greatest length as preserved, proximal 1000
end missing
Greatest width near proximal end 63
Maxillary, greatest length as preserved, in a straight 735+
line
Vomer, greatest breadth as preserved 68
Squamosal, Greatest transverse diameter of zygomatic 295
process, from margin of tympanoperiotic recess to
external margin of squamosal
Greatest length of external edge of zygomatic process, 310
approximately
Tympanic Bulla
The incomplete right tympanic bulla (AMNH 9846)
which Cope (1890, p. 612, fig. 7) described as being
“noticeably compressed, somewhat incurved, and with a
nearly parallelgrammic outline from the side” measures
71.5 mm. in length and 37 mm. in width. These dimensions
are matched by the tympanic bulla of a much smaller
Calvert cetothere (USNM 23494) whose mandible measures
in a straight line 1480 mm. as contrasted with 2326-- mm.
for the mandible of Eschrichtius cephalus. Either fortuitous:
association at the same locality with the type skeletal
remains or subsequent presumptive allocation may ex-
plain this later referal by Cope, since no tympanic bulla
was included in the material received by the Academy
from James T. Thomas.
Periotic
One of the periotic bones (AMNH 1750) mentioned by
Cope (1868a, p. 132) as previously presented to the
Academy quite certainly represents a balaenopterine whale
and is now regarded as belonging to a species different
from Eschrichtius cephalus. The bone is most probably derived
from the Yorktown formation, near Yorktown, Virginia,
and not from Tarboro, North Carolina. This is probably
the periotic bone sent to Cope by Edwin Holway of York-
town, Virginia. The dimensions of this left periotic are
compatible with those of the left tympanic bulla (length,
101 mm.) of Balaenoptera sursiplana (Cope, 1895a, p. 151;
USNM 9347, type).
On this left periotic (fig. 39b) the internal acoustic
meatus and the Fallopian aqueduct open in close proximity
on the internal (cerebral) face. The fenestra rotunda is large
275-699 682.
107
and within it a portion of a semicircular canal is visible
from the posterior view. There is no internal opening for
the aquaeductus cochleae, and only a portion of the shallow
open groove or canal which marks its former course is
present. The orifice of the aquaeductus vestibuli lies just
above and internal to the fenestra rotunda in a slit-like
depression, but is situated much more internally than in
any of the living whalebone whales. The internal acoustic
meatus is deep, circular in outline, and at its base is a
minute foramen, the foramen centrale. The cerebral
opening of the Fallopian aqueduct is about one half the
size of the internal acoustic meatus. The partition between
this aqueduct and the internal acoustic meatus does nor
attain the level of the cerebral face of the periotic. The
entire cerebral surface of the pars labyrinthica is porous.
The rather short anterior process is compressed from side
to side; the posterior process is rather slender and elongated ;
and the pars cochlearts is inflated.
On the tympanic or ventral face (fig. 39a) the anterior
pedicle of the tympanic bulla is fused with the anterior
process of the periotic; behind this attachment the head
of the malleus is lodged in a somewhat elongated depression
which in turn lies below the tympanic orifice of the Fallopian
aqueduct. Behind the fenestra ovalis is the rather large
excavation for the attachment of the stapedial muscle.
Alongside this excavation and external to it the facial
nerve occupies the narrow groove which has its origin at
the orifice of the Fallopian aqueduct, and extends backward
to the posterior edge of the pars labyrinthica; on its outward
course this nerve then occupies the broad groove on the
+. ventral face of the posterior process.
Measurements (in mm.) of the left periotic (AMNH 1750)
are as follows:
Greatest length, tip of anterior process to tip of posterior i50.8
process
Length of posterior process (opisthotic), external wall 89
of the groove for the facial nerve to tip of posterior
process
Greatest anteroposterior diameter of posterior process 30
Greatest vertical diameter of posterior process 50
Width of periotic from internal face to external face 59.6
Anteroposterior distance from tip of anterior process 86
(prootic) to posterior face of pars labyrinthica behind
groove for stapedial muscle
Anteroposterior diameter of pars cochlearis, from antero- 43
internal angle to anterior edge of fenestra rotunda
Mandible
The mandibles of the type specimen (ANSP 12691) are
larger than those of all cetotheres found in the Calvert
formation and exhibit a rather close resemblance to the
mandibles of a young finback (Balaenoptera physalus).
108
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 5
Ficure 40.—Views of right mandible, ANSP 12691, of Eschrichtius cephalus Cope: a, external view; 6, dorsal view. Abbrs.: cor., coronoid
process; f.g., gingival or alveolar foramen; f.m., mental foramen.
They also differ from mandibles of Calvert cetotheres in
having the vertical diameter of the ramus (fig. 40a) strongly
diminished from in front of the coronoid process toward
the anterior end. Both of the type mandibles are broken
transversely at several places, the right one being broken
at the following distances from the anterior end: 200 mm.,
700 mm., 1950 mm., and 2325 mm. The anterior end of
the right mandible is complete, but most of the coronoid
process and a portion of the ramus behind the latter,
including the condyle, is destroyed. The missing portion
of the ramus did not exceed 300 mm. in length.
The horizontal ramus of the mandible (fig. 40b) is
bowed outward, most conspicuously in front of the middle
of its length, and the maximum distance between the
alveolar margins of the opposite rami is probably greater
than the width of the rostrum at corresponding levels.
Cope (1869, p. 10) described the mandibles as being
‘‘much depressed, outer face little convex; superior margin
a narrow ridge without any truncation, with a series of
foramina on each side, the inner extending for a very
short distance only; no marginal groove; inferior edge
narrow. Very large.” Actually the internal surface of
each mandibular ramus is distinctly flattened but the
external surface, however, is rather strongly convex (see
fig. 41; also, Cope, 1896, pl. 12, figs. 2-3). The relatively
short symphysial region is not pitted for the attachment of
ligaments. The curved internal ledge at the anterior end of
the ramus, which on the right mandible is located about
50 mm. below the corresponding point of the dorsal margin
anteriorly and 96 mm. posteriorly, is discernible for a
distance of 290+ mm. At the anterior end of the ramus,
25 mm. below the dorsal edge, there is a deep groove that
leads backward to the large trumpet-shaped orifice of the
mandibular canal.
The external mental foramina are relatively large, the
hindermost one on the left mandible being 14 mm. in
diameter, 37 mm. below the dorsal ridge, and 155 mm.
behind the next anterior foramen. Each of these foramina
opens into a deep groove, which not only is directed |
anteriorly, but also increases in width from its point of
origin to the point where it becomes indistinct. The |
internal gingival foramina are small, 3 to 4 mm. in diameter,
and posteriorly are located about 25 mm. below the dorsal
ridge and from 30 to 80 mm. apart. These internal gingival
foramina run up onto the dorsal surface on the anterior —
t
Ficure 41.—Cross sections of right mandible, ANSP 12691, of
Eschrichtius cephalus Cope; a, 100 mm. behind anterior end;
6, 300 mm. behind anterior end; c, 500 mm. behind anterior
end; d, 1000 mm. behind anterior end; e, 1500 mm. behind
anterior end; f, 2000 mm. behind anterior end.
MIOCENE CALVERT MYSTICETES 109
one fourth of the ramus. The anteriormost one of these
small internal gingival foramina is located on the dorsal
edge about 165 mm. behind the anterior end of the ramus,
but the succeeding ones gradually drop down to a lower
level, the hindermost one being at least 25 mm. below
the dorsal ridge and at least 470 mm. anterior to hinder
edge of the coronoid process.
The coronoid process, judging from the basal portion,
when complete may have resembled somewhat closely the
same process on the mandible of a 45-foot long Balaenoptera
physalus (USNM 16039). Apparently, the coronoid process
was outwardly curved, with apex anterior to anteriormost
edge of entrance to the large mandibular canal. It should
be noted, however, that Cope (1868 b, p. 149) stated that
the coronoid process was broken off when received, but the
base indicated that it was compressed and not elevated.
The outer wall of the ramus between the coronoid process
and the condyle was, apparently, merely a very thin shell
(thickness 5 to 25 mm.) in contrast to the swollen and
conspicuously thickened hinder portion (thickness 98 mm.)
of the ramus of the young Balaenoptera physalus.
Measurements (in mm.) of the mandibles are as follows:
Eschrichtius cephalus Balaenoptera
physalus
ANSP ANSP USNM
12691 12691 16039
Right Left Right
Greatest length of mandible 2326 -+- 2325+ 2610
as preserved, in a straight
line
Greatest length of mandible 2370+ 2385+ 2720
as preserved, along out-
side curvature
Greatest vertical diameter of 117 119 126
mandible, 100mm. behind
anterior extremity
Greatest transverse diameter 56 54 72
of mandible, 100 mm. be-
hind anterior extremity
Greatest vertical diameter 118 120 130
of mandible, 300 mm. be-
hind anterior extremity
Greatest transverse diameter 59 58 82
of mandible, 300 mm. be-
hind anterior extremity
Greatest vertical diameter of 119 118 131
mandible, 500 mm. behind
anterior extremity
Greatest transverse diameter 70 70 84
of mandible, 500 mm. be-
hind anterior extremity
Greatest vertical diameter of 151 149
mandible 1000 mm. be-
hind anterior extremity
147.5
Eschrichtius cephalus Balaenoptera
physalus
ANSP ANSP USNM
12691 12691 16039
Right Left Right
Greatest transverse diameter 92 91 105
of mandible, 1000 mm. be-
hind anterior extremity
Greatest vertical diameter of 199 192 192.5
mandible, 1500 mm. be-
hind anterior extremity
Greatest transverse diameter 102 111 117
of mandible, 1500 mm.
behind anterior extremity
Greatest vertical diameter 209 205 204
of mandible, 2000 mm.
behind anterior extremity
Greatest transverse diameter 87 86 119
of mandible, 2000 mm.
behind anterior extremity
Greatest vertical diameter of 212+ 216+ 330
mandible through coronoid
process
External mental foramen
(mm. behind anterior
extremity)
First = 100 =
Second 705 740 710
Third 897 1115 1045
Fourth 1108 1398 1190
Fifth 1331 1565 1410
Sixth 1480 1661 1495
Seventh 1679 1842 1546
Eighth 1911 _ 1604
Ninth —_ — 1815
Vertebrae
CERVICAL VERTEBRAE.—Four (ANSP 12692) of the five
cervical vertebrae described by Cope as having been found
in association with the mandibles and the skull fragments
have well-preserved centra, but lack most of their processes.
The axis and the third cervical were not found. All of these
vertebrae have both epiphyses attached to the centra.
Atlas: The atlas (ANSP 12941), as mentioned by Cope
(1868b, p. 148), exhibits a rather close resemblance to the
corresponding cervical of Balaenoptera acutorostrata. ‘This
resemblance is most marked in the relative transverse
diameter of the neural canal, the ventral position of the
transverse processes, and the obliquity of the cuplike
anterior articular face of the centrum. These anterior
articular facets are separated ventrally by an interval of
25 mm. In this interval, there is a transverse, very obtuse
tuberculum atlantis. The transverse process is compressed
110
Ficure 42.—Anterior view of fourth cervical, ANSP 12692, of
Eschrichtius cephalus Cope. Abbrs.: d.a., diapophysis; p.a.,
parapophysis.
anteroposteriorly and perforated at the base by a verte-
brarterial canal. The neural spine is not developed. The
measurements (in mm.) are as follows: greatest vertical
diameter, tip of vestigial neural spine to ventral face of
centrum, 163; and greatest vertical diameter of neural
canal anteriorly, 95.
Fourth Cervical: The centrum (ANSP 12692; fig. 42) is
subrectangular in outline, convex anteriorly and concave
posteriorly. The neural arch is destroyed except for the
basal portion of the left pedicle and of the anteroposteriorly
compressed left diapophysis. The obliqueness of the down-
ward slope of the exteroventrally directed parapophyses
Ficure 43.—Anterior view of fifth cervical, ANSP 12692, of
Eschrichtius cephalus Cope. Abbrs.: d.a., diapophysis; p.a.,
parapophysis.
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 5
renders it improbable that the para- and diapophyses were
connected distally to inclose the vertebrarterial canal.
The slender parapophyses are anteroposteriorly compressed.
The maximum diameter of the neural canal is 101 mm.
The anterior profile of the centrum of the corresponding
cervical of B. acutorostrata (USNM 256498) is a flattened
elliptical oval.
Fifth Cervical: The anterior face of the centrum is more
subquadrate in outline (ANSP 12692; fig. 43) than the
preceding, convex anteriorly and concave posteriorly.
The neural arch is destroyed except for the basal portion
of the left pedicle; the anteroposteriorly compressed base
of the right diapophysis is also preserved. The parapophyses
are directed more downward than those on the fourth
cervical and probably were not connected distally by an
osseous isthmus with the diapophysis. The floor of the
neural canal is more flattened than on the sixth and seventh
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Ath
Nt
AN
Figure 44.—Anterior view of sixth cervical, ANSP 12692, of
Eschrichtius cephalus Cope. Abbrs.: d.a., diapophysis.
cervicals. The anterior profile of the centrum of B. acutoro-
strata is more nearly elliptical.
Sixth Cervical: The centrum (ANSP 12692; fig. 44) is
ovoidal in outline viewed from in front, convex anteriorly,
and concave posteriorly. Except for the basal portions, the
pedicles of the neural arch and the conjoined anteropos-
teriorly compressed diapophyses are destroyed. The
diapophyses appear to have been bent backward to some
extent. No vestige of the parapophysis persists. The broad
floor of the neural canal is elevated medially. The width
of the elliptical anterior face of the centrum of the corre-
sponding cervical of B. acutorostrata is relatively greater than
the transverse diameter of the centrum of this fossil cervical.
Seventh Cervical: The profile of the anterior face of the
centrum (ANSP 12692; fig. 45) is broadly subovate and
the broad floor of the neural canal is less elevated medially
than on the preceding cervical. All of the neural arch,
MIOCENE CALVERT MYSTICETES 111
‘forelimb was remarkably short, approaching the species
of Balaena, and differing from £. robustus, still more from
the Sibbaldii and Balaenopterae and most from Megaptera
longimana.”*
Figure 45.—Anterior view of seventh cervical, ANSP 12692, of
Eschrichtius cephalus Cope. Abbrs.: d.a., diapophysis.
except the basal portions of its pedicles, is missing. The
anterior face of the anteroposteriorly compressed basal
portion of the diapophysis is excavated and is inclined
slightly forward. The parapophysis was not developed. A
greater relative width and a more elliptical anterior outline
of the centrum distinguish the same cervical of Balaenoptera
acutorostrata from the seventh cervical of this fossil mysticete.
Measurements (in mm.) of the cervical vertebrae are as
follows:
C4 C5 C6 C.7
Anteroposterior diameter of centrum 20 22 22 29
Vertical diameter of centrum 103 108 #£«4110 108
anteriorly
Transverse diameter of centrum 118 120 120 137
anteriorly
CAUDAL VERTEBRAE.—Neither of the two caudal vertebrae
listed by Cope (1868b, p. 149) are structurally unlike those
of other mysticetes. The larger caudal, possibly the fourth
or fifth, has the anterior and posterior haemal tubercles on
either side of the longitudinal groove or channel for the
caudal artery connected by an osseous isthmus. The distally rf 7
eroded lateral tansverse processes projected outward more
than 40 mm. beyond the centrum.
The measurements (in mm.) of this caudal (ANSP 12941)
are as follows: anteroposterior diameter of centrum, 131;
transverse diameter of centrum anteriorly, 143; and vertical
diameter of centrum anteriorly, 121.
ey:
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1 ty
HT
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a0
1
hl
Drs. i oro
LN
Forelimb
e i Z : Ficure 46.—Views of left humerus, ANSP 12691, of Eschrichtius
The forelimb is relatively short, the combined length of cephalus Cope: a, external view; b, view of distal end. Abbrs.:
the humerus and radius being slightly more than 27% h, head; r-f., radial facet; r.t., radial or greater tuberosity; u.f.,
inches (692 mm.) Cope states (1868b, p. 150) that the ulnar facet.
112 UNITED STATES NATIONAL MUSEUM BULLETIN 247
Humerus.—The type left humerus (ANSP 12691) is com-
plete with the exception of eroded areas on the proximal
end. The greater tuberosity (fig. 46a) is eroded and a
considerable portion is missing. On the proximal end there
is a large circular eroded area at least 80 mm. in diameter
and 10 to 15 mm. in depth which commences on the anterior
border of the head and extends forward about half way
across the internal face of the shaft. A similarly eroded area
of approximately half the diameter of the above-mentioned
area is present on the internal face below the greater
tuberosity.
An unassociated left humerus (USNM 180) tentatively
referred to this mysticete has the internal face of the head
eroded, the greater or radial tuberosity is more noticeably
worn, and a considerable portion of the distal facet for the
olecranon of the ulna is eroded.
The anteroposterior width of the side to side flattened
type left humerus exceeds the corresponding measurement
of recorded Miocene cetotheres. Although it differs from
the left humerus of the lower Pliocene Belgian Plesiocetus
hupschii figured by Van Beneden (1885, pl. 24, figs. 2-3)
in important details, the main dimensions of the Calvert
humerus are approximately the same as the latter. On the
humerus of P. hupschii there is a large triangular facet on
the posterior face of the distal end of the shaft for articulation
with the olecranon process of the ulna; the external face
lacks the elevation for muscular attachment, and the greater
tuberosity is reduced and does not project dorsal to the
level of the articular head but is obliquely truncated in a
dorsoanterior direction.
Both epiphyses of the type left humerus are firmly fused
with the shaft. The head (fig. 46a) is subelliptical in out-
line, placed obliquely on the shaft, facing outward and
backward. The rough and pitted articular surface on the
head is set off from the shaft by bone of a quite different
texture; the general appearance of the head suggests that
it was enveloped by capsular cartilage. The greater tuber-
osity is imperfectly preserved on the type humerus as well
as on the referred humerus (USNM 180), but enough
remains to indicate that it was well developed.
Both of these humeri have an elevation near the middle
of the external face for muscular insertion, possibly the
short head of M. triceps. Viewed from the external side
(fig. 46a), the anterior profile, with the exception of the
greater tuberosity, is nearly straight, while the posterior
profile is strongly concave, with the deepest indentation at
level of the above-mentioned elevation. At the proximal
end of the shaft on the internal face between the head and
the greater tuberosity is a large rounded protuberance,
possibly in part for the insertion of M. supraspinatus. The
anterior or radial face of the shaft is rather thick and con-
vexly curved from side to side. The hinder face of the shaft
is somewhat broader and more flattened. The distal end
PART 5
of the shaft is more strongly expanded anteroposteriorly
on the type humerus than on the larger referred left humerus.
On the distal end of the shaft (fig. 46b) the ulnar articular
surface is slightly larger than the radial facet and these
two facets are separated by a low transverse crest. The
ulnar facet has the shape of an unsymmetrical saddle and
extends upward on the hinder face of the distal end of the
shaft for a short distance. It is slightly concave from side
to side and meets the radial facet at an obtuse angle. Both
the radial and ulnar facets are deeply pitted.
Measurements (in m.m.) of the humerus are as follows:
Eschrichtius cephalus Plesiocetus
——— SS Bite
ANSP USNM MHNB
12691 Left 180 Left 99 Left}
Greatest length of humerus 296 318 300
Greatest anteroposterior di- 155 177+ =
ameter of proximal end
Greatest anteroposterior di- 130.5 140 136
ameter of head
Greatest exterointernal 116 133 =
(transverse) diameter of
head
Least anteroposterior di- 112 131 108
ameter of shaft
Least exterointernal (trans- 76.5 75 —
verse) diameter of shaft
Greatest anteroposterior di- 136 162 135
ameter of distal end
Greatest exterointernal 74 O15 82
(transverse) diameter of
distal end
Greatest anteroposterior di- 77 92 _
ameter of radial facet
Greatest anteroposterior di- 80 99=5 —
ameter of ulnar facet
1 Measurements from Van Beneden, 1885, pl. 24, figs. 2-3.
Raprius.—At the proximal end the epiphysis is firmly
ankylosed to the shaft of the left radius (ANSP 12691); a
portion of the distal end of the shaft is broken off and lost.
This limb bone (fig. 47a) when complete was longer than
that of Pelocetus calvertensis (Kellogg 1965, p. 39, fig. 23a)
and the anteroposterior diameter (89.5 mm.) of the prox-
imal end exceeded slightly the corresponding measurement
(84 mm.) of the right radius of P. calvertensis. The somewhat
flattened shaft is most strongly bent backward on the prox-
imal third of its length. The proximal facet (fig. 47b) which
articulated with the radial facet of the humerus is shallowly
concave and its anteroposterior diameter is greater than
MIOCENE CALVERT MYSTICETES
Ficure 47.—Views of left radius, ANSP 12691, of Eschrichtius
cephalus Cope: a, internal view; 6, view of proximal end. Abbrs.:
ant., anterior face; pt., posterior face.
113
its transverse diameter. An indentation on the posterior
face of the proximal end marks the location of the articular
area for its contact with the ulna. The internal and external
faces of the shaft are slightly convex.
Measurements (in mm.) of left radius, ANSP 12691 are
as follows: Greatest length, 396; anteroposterior diameter
of proximal end, 89.5; transverse diameter of proximal end,
64.5; anteroposterior diameter of distal end, 110; trans-
verse diameter of distal end, 53.
Utna.—A large right ulna (USNM 23749) that has the
shaft broken off 280 mm. below the horizontal articular
surface of the olecranon fossa and a considerable portion
of the posterior border of the olecranon process eroded is
tentatively referred to this mysticete. This ulna is more
massive, larger, and presumably longer than those of all
other Calvert Miocene mysticetes and probably belonged
to a larger individual than the type. Viewed from the side,
the posterior profile is slightly more curved than the an-
terior profile. In cross section the shaft is ovoidal and not
transversely compressed; the minimum anteroposterior
diameter of the shaft is 66 mm., and the minimum trans-
verse diameter is 48 mm. The enlarged and thickened
olecranon process is bent inward and this curvature modifies
the direction of the upper, more vertical portion of the
articular surface of the greater sigmoid cavity. The trans-
verse diameter of the horizontal articular surface is 64 mm.,
and the width of the upper articular surface is about 50 mm.
Manus.—The position and homologies of the two carpal
bones (ANSP 12691) associated with the humerus and
radius are uncertain. The preservation of these two in-
dicates that some if not all of the five or six carpal bones
comprising the manus were ossified. These carpal bones
have their flexor and extensor surfaces flattened and their
irregular circumferential borders pitted and roughened
for attachment of the intervening cartilaginous tissue which
normally in Recent mysticetes occupies the interspaces
between them. The greatest dimension of the largest carpal
is 63.5 mm.
The single phalange is noticeably flattened, slightly
constricted near the middle of its length, and widened
distally. Both ends are roughened for the attachment of the
cartilaginous tissue that connects the phalanges of each
finger enclosed within the integument of the flipper.
This finger bone measures 80.5 mm. in length and 57 mm.
in width.
ESCHRICHTIUS PUSILLUS Cope
Balaenoptera pusilla Cope, 1868c, Proc. Acad. Nat. Sci. Philadelphia,
vol. 20, no. 3, p. 159. [Nomen nudum.]
Eschrichtius pusillus Cope, 1868d, Proc. Acad. Nat. Sci. Philadelphia,
vol. 20, no. 3, p. 191
Cetotherium pusillus Cope, 1890, American Nat., vol. 24, no. 283,
pp. 612, 616. [Antedated by Cethotherium pusillus Alexander
114
von Nordmann, Palaeontologie Siidrusslands, p. 348, pl. 28,
figs. 6, 6a, 1860; a second cervical from Taman and the
vicinity of Kertsch, Bessarabia. ]
Cetotherium parvum ‘Trouessart, Catalogus mammalium tam
viventium quam fossilium, Berlin, fasc. 5, p. 1071, 1898.
[To replace C. pusillus Cope, antedated.]
Type Specimen: Many vertebrae, ‘‘of which one dorsal,
six of the lumbars, and one caudal may serve as types,”
ANSP 12769; and a fragment of a right mandible (length,
381 mm.), not since located in the collection of the Academy
of Natural Sciences of Philadelphia. Collector, James T.
Thomas.
Type Locality: Presumably excavated in a marl bed on
the De la Brooke estate, about 1 mile east of site marked
Patuxent (U.S.G.S. Brandywine sheet), 2 miles east of
Hughesville, Charles County, Maryland. Calvert formation,
middle Miocene.
Diagnosis: Cope (1868c, p. 159) announced the presenta-
tion to the Academy of Natural Sciences of Philadelphia of
a portion of the mandible of the smallest known finner
whale whose length was about 18 feet which he named
Balaenoptera pusilla, and commented that ‘“‘some vertebrae
in the collection were also supposed to belong to the same.”
Later the same year, when Cope (1868d, pp. 191-192)
published the detailed description and measurements of
this right mandible (length, 15 inches [381 mm.]; depth,
2 inches [50.8 mm.]; circumference, 5 inches 2.5 lines), he
referred to this mysticete under the designation Eschrichtius
pusillus. Cope (1868d, p. 191) also stated that ‘‘this species
is indicated by many vertebrae of which one dorsal, six of
the lumbars, and one caudal may serve as types.’? Some
years later at least 28 cetacean vertebrae which were
available for examination, when the descriptions of both
E. pusillus and Megaptera expansa were published, were
assigned the same catalog number (ANSP 12769). Among
these vertebrae were the centra of a first dorsal, a posterior
dorsal, four lumbars, and 2 caudals which presumably were
regarded as belonging to Eschrichtius pusillus by Cope. The
measurements published by Cope (1868d, p. 192) were
relied on in selecting one dorsal, one lumbar, and one
caudal from this assemblage for allocation to E. pusillus.
No dorsal vertebra having dimensions that correspond
precisely to those published by Cope (1868d, p. 192) was
recognized among the vertebrae (ANSP 12769) listed
under this species in the catalog of the Academy. Converted
measurements (in mm.) are as follows: length, 125; height
of articular face, 89; width of articular face, 108; width of
neural canal, 34. There is in this lot a posterior dorsal,
probably the tenth or eleventh, with epiphyses firmly
ankylosed to the centrum that has the anterior articular
end ovoidal in outline, but only basal remnants of the
pedicles of the neural arch and the transverse processes.
Measurements (in mm.) of this dorsal (pl. 46, fig. 3) are
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 5
as follows: anteroposterior diameter of centrum, 128;
vertical diameter of centrum posteriorly, 88; transverse —
diameter of centrum posteriorly, 109; and transverse |
diameter of neural canal, 34+.
The ‘“‘depressed oval” shape of the end and regular
curvature of the centrum ventrally, mentioned by Cope,
apply equally well to this vertebra. A dorsal vertebra of
these dimensions would indicate a cetothere comparable
in size to Pelocetus calvertensis.
The lumbar (pl. 46, fig. 1) is described by Cope as having
the usual ventral longitudinal keel, the articular end
“not quite so transverse,”’ and small not noticeable venous
canals. The measurements (converted in mm.) are given
as follows: length, 125; height articular surface, 99; width
articular surface, 106; and width of neural canal, 21.
One lumbar of a mature individual that retains remnants
of the pedicles of the neural arch and of the rather broad
transverse processes can be described in the above terms;
its measurements, however, are less in agreement. They
are as follows: anteroposterior diameter of centrum, 127;
vertical diameter of centrum anteriorly, 100; transverse
diameter of centrum anteriorly, 119; and transverse
diameter of neural canal, 26+. A large, but a slightly
smaller whale is indicated than the one that had the
preceding dorsal.
As regards the caudal vertebra, Cope states that the
transverse processes are not perforated at the base, the
ventral longitudinal keels are very slight, and the neural
arch occupies three-fifths the length of the centrum.
The published measurements (converted in mm.) are as
follows: length, 102; height articular surface, 96; width
articular surface, 101; height to zygapophyses, 131. One
caudal (ANSP 12769; pl. 46, fig. 2) in the Academy’s
collection has quite similar measurements (in mm.), as
follows: anteroposterior diameter of centrum, 102; vertical
diameter of centrum anteriorly, 99; transverse diameter
of centrum anteriorly, 100; and zygapophyses to ventral
face of centrum, 131. This caudal vertebra, however,
belonged to a somewhat smaller whale than either the
lumbar or the dorsal; it lacks both epiphyses, the transverse
processes are broken off at the base, as are also the meta-
pophyses and the neural spine. This fourth or fifth caudal
lacks developed anterior haemapophyses; the rather broad
posterior haemal tubercles bound the shallow longitudinal
haemal groove. The profile of the posterior face of the
centrum approaches hexagonal more closely than that of
the anterior face.
Two at least and possibly three different species of
cetotheres are represented among the eight vertebrae which
presumably were referred to E. pusillus by Cope (1868d,
pp. 191-192).
There is no certainty that the following description
published by Cope (1869, p. 11) was based on the type
MIOCENE CALVERT MYSTICETES 115
Ficure 48.—Views of right mandible, ANSP 12912, labeled Eschrichtius pusillus Cope: a, external view; 6, dorsal view; c, cross section 210
behind broken anterior end. Abbrs.: c.a., alveolar or mandibular canal; f.g., gingival or alveolar foramen; f.m., mental foramen.
mandible: ‘‘upper edge nowhere broad and with a deep
or shallow groove below it on inside; less decurved; less
convex externally; small.”
The mandible from the mouth of the Patuxent River
corresponding to the cited measurements and referred by
Cope (1869, p. 11) to this species was not located in the
collections of the Academy. This mandible, according to
Cope (1869, p. 11), “differs from the type in having the
inner groove on the superior margin much less marked.”
On the preceeding page, Cope (1869, p. 10) attributes
provisionally to E. pusillus a portion of a black cranium
(St. Marys fm.) which “serves to confirm the affinities
expressed in the name established on the ramus of the
mandible.”
There is, however, a section of a right mandible (ANSP
12912; figs. 48a, b, 463 mm.) in length from Charles
County, Maryland labelled ‘“‘Cetotherium pusillum Cope,
Type,” which is black in coloration and undoubtedly
was derived from the St. Mary’s formation in that region.
At a point 210 mm. behind the broken anterior end of this
mandible (fig. 48c), the vertical diameter is 67 mm. and
the transverse 44.5 mm. Right and left mandibles (ANSP
12918), measuring respectively 1107 mm. and 1063 mm.
in a straight line as preserved, are also labelled as from
near the mouth of the Patuxent River and presumably were
found either in the Calvert or the Choptank formation.
Nevertheless, neither of these mandibles (ANSP 12912
and ANSP 12918) are specifically mentioned in the several
references made to this species by Cope.
In review it should be noted that although Cope (1868c,
p. 159) originally applied the name Balaenoptera pusilla to
a portion of the right mandible; vertebrae in the collection
of the Academy were “‘supposed”’ to belong to the same
species. Writing in the next month of the same year, Cope
(1868d, p. 191) specifically designated eight vertebrae
which “may serve as types,’? and commented that vertebrae
of several small species were procured by J. T. Thomas;
and since they are “the most abundant and therefore
characteristic of the beds, I think best to describe them
from these.” A year later Cope (1869, pp. 10-11) une-
quivocally stated that the name fpuszllus was ‘established
on the ramus of the mandible.” This mandible, however,
belonged to a smaller species of mysticete than the vertebrae.
The vertebrae of the type series of EF. pusillus are devoid of
all processes and hence any allocation must be made on
the configuration and comparative demensions of the
centra.
Subsequent acquisition of additional specimens led Cope
(1869, p. 10) to recognize six species of Eschrichtius, “whose
characters offer nothing as yet to separate them from the
scarcely extinct type E. robustus Lillj.” and of these five
were characterized by their mandibles as set forth in an
accompanying table. It is now certain that not one of the
mandibular types of the fossil mysticetes referred to Esch-
richtius by Cope exhibits even a remote resemblance to the
mandible of Eschrichtius robustus.
More than twenty five years later, Cope (1895a, p. 145)
shifted his generic allocation of this mysticete to Cetotherium
116
pusillus and commented on an incomplete mandible
“Jonger than any that have come under my observation,
which now number five individuals. Its length is 723 mm.,
and the diameters at a fracture near the middle are as
follows: vertical, 71 mm.; transverse, 47 mm. It is a little
larger than those that I have seen hitherto, but agrees with
them in every respect.’’ This mandible, USNM 9351, is
recorded as from near the mouth of the Patuxent River,
Maryland.
The original 381 mm. long portion of a right mandible
was described by Cope (1868d, p. 192) as differing from
the type mandible of Balaena prisca Leidy by the presence
of a median dorsal ridge paralleled by a groove on the
internal side into which the small gingival or nutritious
foramina open. This groove has no especial significance
since it is present on several mandibles of obviously different
cetotheres. Furthermore, this ramus was moderately convex
on both faces, the outer face more so than the inner, and its
size was about ‘one third the same portion of the jaw of
B. prisca.”’ A vertical diameter of two inches (50.8 mm.) is
given by Cope for this type mandible of E. pusillus, which
is about two thirds of the corresponding measurement
(72 mm.) of the type mandible of B. prisca.
In summary, the nondiagnostic characterization of the
type mandible (apparently lost) and of the eight vertebrae
mentioned by Cope and the uncertainty relative
to the particular vertebrae selected by Cope for specific
designation among the mixed assortment of 28 vertebrae,
which may represent two or possibly three different
cetotheres, render it difficult if not impractical to formulate
a satisfactory diagnosis by which this species could be
discriminated. Since the validity of Eschrichtius pusillus can
not be satisfactorily demonstrated by critical comparisons
with a rather unusual varied assemblage of Calvert
cetothere skeletal materials, the name should be ignored
and discarded.
MEGAPTERA Gray
Megaptera Gray, 1846, Ann. Mag. Nat. Hist., London, ser. 1,
vol. 17, no. 10, p. 83. February 1846.
Type Species: Megaptera longipinna Gray (—Balaena
longimana Rudolphi = Balaena novae angliae Borowski, 1781
Gemeinnmiizzige Naturgeschichte des Thierreichs . . .,
vol. 2, pt. 1, p. 21).
Type Specimen: Based on Balaena novae angliae Brisson,
1762, Regnum Animale, Leyden, p. 221. The Pflokfisch,
the humpback whale. New England.
Diagnosis: This genus was characterized by Gray (1864,
p. 350) as follows:
“The hunchbacked whales have a very low broad dorsal, a
very long pectoral fin; arm bones strong, broad; fingers very
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 56
long, joints 3 to 10; the cervical vertebrae are often anchylosed;
the neural canal high, triangular, with angles rounded, as high
as broad.
The pectoral fin about one-fifth of the entire length of the
animal. The second cervical vertebra with two short, truncated,
subequal lateral processes. Ribs 14, first single-headed. Vertebrae
DOTIOE/ DOs
MEGAPTERA EXPANSA Cope
Megaptera expansa Cope, 1868d, Proc. Acad. Nat. Sci. Philadelphia,
vol. 20, no. 3, p. 193.
Eschrichtius expansus Cope, 1869, Proc. Acad. Nat. Sci. Philadelphia,
vol. 21, no. 11, p. 11.
Cetotherium expansus Cope, 1890, American Nat., vol. 24, no. 283,
p. 616.
Stphonocetus expansus Cope, 1895a, Proc. American Philos. Soc.,
Philadelphia, vol. 34, no. 147, p. 140, pl. 6, fig. 5.
Type Specimen: Cervical vertebrae, ten dorsal vertebrae,
and several lumbar vertebrae. The following are co-types
in Cope’s original description: (1) numerous vertebrae col-
lected by James T. Thomas, (2) several vertebrae collected
by Oliver N. Bryan, and (3) some vertebrae from Virginia
in the collection of the Academy. The anterior and median
dorsal vertebrae, for which measurements are published by
Cope (1868d, p. 193), are now designated as the lectotype,
ANSP 12769.
Type Locality: Not designated: original description based
on vertebrae from three localities, including (1) ‘numerous
vertebrae’ found near the Patuxent River, not far from
the home of James T. Thomas, which was located about
1 mile east of site marked Patuxent (U.S.G.S. Brandywine
sheet), 2 miles east of Hughesville, Charles County, Mary-
land, Calvert formation; (2) ‘‘several vertebrae” from
Nomini Cliffs, Westmoreland County, Virginia, presented
to the Academy by Oliver N. Bryan [of Marshall Hall,
Charles County, Maryland] and probably from Calvert
formation; and (3) vertebrae from Virginia.
Diagnosis: The diagnostic criteria for Megaptera quoted
by Cope (1868b, p. 147) are “transverse processes and para-
pophyses of second and succeeding cervical vertebrae always
separate and not united at their extremities;’’ and those of
second cervical usually very broad at their origins. Cope
(1868d, p. 193) did not describe the cervicals of M. expansa
which he remarked were not in his possession at that time.
These cervicals are characterized, however, by Cope, as
having a greater anteroposterior diameter than those of
Eschrichtius, but possessing quite similar di- and para-
pophyses. Two dorsal vertebrae (ANSP 12769) alone among
the 28 vertebrae acquired for the collections of the Academy
before and during 1868 exhibit sufficiently close agreement
with the measurements and brief description published by
Cope (1868d, p. 193) to be regarded as the original speci-
MIOCENE CALVERT MYSTICETES 117
mens. The measurements (in mm.) of these two vertebrae,
which agree most closely with the fifth and ninth in the
dorsal series, are as follows, respectively: anteroposterior
diameter of centrum, 70, 82; transverse diameter of centrum
anteriorly, 103+, 93; vertical diameter of centrum anteri-
orly, 68, 77; and transverse diameter of neural canal, 46,
31. On the vertebra regarded as the fifth dorsal, the dia-
pophysis projects outward from the pedicle of the neural
arch; each posterodorsal lateral demifacet is large and
protuberant. Concave lateral surfaces accentuate the pro-
jecting circumferential rims of articular ends of the centrum.
The transverse process of the ninth projects from the
dorsolateral surface of the centrum, the normal condition.
Various mysticetes have vertebral centra with more or less
subcordate articular ends. Among the European species
those of M. expansa seem to exhibit the nearest resemblance
to those of Mesocetus longirostris (Van Beneden, 1886, pl. 40),
with which several agree rather closely in size. Cope’s
comments on the dorsal and lumbar vertebrae have no
special significance except to indicate size and general
appearance.
In 1869, Cope transferred this species to the genus
Eschrichttus and referred to it some limb bones and three
pieces of mandibles of two individuals from the mouth of
the Patuxent River, in Maryland, incorrectly stated to
belong to the collection of P. T. Tyson of the Geological
Survey of Maryland. He did not describe the limb bones,
but gave a description and measurements of one mandibular
fragment from which it appears that the chief peculiarity
of the ramus was the flat upper surface of the proximal
portion in which the internal gingivalforamina were
located. According to Cope (1869, p. 11) “‘the inferior
margin is a rather obtuse angle; the general form is not
compressed, nor much convex externally, as in E. priscus.”
In the comparative table of the diagnostic features of four
species referred to Eschrichtius the mandible of E. expansa
was characterized as having “upper edge broad behind
only and these bearing only the inner series of foramina.
Elsewhere with a median ridge and rows of foramina below
on each side; much decurved; less convex externally.
Medium.” The mention made here to the “‘median ridge
[anterior to the broad flat upper surface] and the rows of
foramina below on each side” indicates in that year Cope
attributed some significance to the position of the lateral
rows of foramina.
At a later date Cope (1895a, p. 140) again revised the
generic allocations of some of the Calvert mysticetes and
transferred expansus to the new genus Siphonocetus which
was characterized by having the alveolar groove and
dental canal distinct, and also the alveolar groove roofed
over and perforate. True (1912, p. 5) suspected that
“these characters are of no value.” Further critical com-
ments are cited under Siphonocetus.
Cope (1895a, p. 140) also remarks that the two mandib-
ular fragments first described (Cope, 1869, p. 11) were
the property of the Maryland Academy of Sciences, and
that there was another smaller fragment (Cope, 1895a,
pl. 6, fig. 5) in the collection of Johns Hopkins University.
This right mandible fragment was labeled Cetotherium
expansum in Cope’s handwriting and marked 15,” formerly
in the Johns Hopkins University collection (now USNM
12722), and measures 175 mm. in length. It is more convex
externally at the anterior end than shown in the illustration
published by Case (1904, pl. 25, fig. 3). There are no
external mental foramina, but the internal single gingival
row is about 10 mm. below the dorsal margin. One cannot
be certain whether or not there are separate mandibular
and gingival canals, although at the anterior end there is a
grayish indurated sandy filling about 7 mm. broad below
the dorsal border of the ramus and below the filling, but
separated by a bony layer, is a deep concavity not so filled.
The latter is certainly the mandibular canal. The blackish
color of this short mandibular fragment suggests that it
was derived from the St. Marys formation of St. Marys
County, southern Maryland.
Inasmuch as the fossil remains on which M. expansa was
established consisted solely of vertebrae, the allocation of
portions of mandibles from several sources in the absence
of associated skeletal elements would appear to require
more justification than advanced by Cope. Accumulated
materials have since shown that some of the original type
vertebrae of M. expansa (although part of an obviously
mixed assortment) are questionably separable from those
of Eschrichtius pusillus. The fact that the internal gingival
foramina are described as being located on the dorsal
flattened surface of the mandible would indicate that Cope,
at that time, did not attach much significance to their
being below the median dorsal ridge in other specimens.
These internal foramina usually begin proximally on the
internal side and gradually approach or rise to the dorsal
margin, ending by crossing over the margin at the distal
extremity of the mandibular ramus. One would expect,
therefore, to find these foramina close to or on the margin
in some pieces of the mandible and lower down on others.
The Belgian species Mesocetus pinguis (Van Beneden, 1886,
pl. 44, figs. 1, 2) shows this kind of an arrangement. If one
takes into consideration the extent of erosion on this
mandibular fragment, a more plausible interpretation of
the location of these foramina becomes obvious. The wear-
ing down of the median longitudinal ridge has flattened
somewhat the dorsal surface of the ramus; the gingival
foramina were, however, actually below this surface when
the ramus was unworn.
Among the ten dorsal vertebrae mentioned by Cope
(1868d, p. 193) as originally included among the numerous
vertebrae in the Thomas collection from Charles County,
118
Maryland, and from the Nomini Cliffs, Westmoreland
County, Virginia, presented by Oliver N. Bryan, are two
dorsals whose measurements were given in the type descrip-
tion of Megaptera expansa. One of these two dorsals, the
ninth (pl. 46, fig. 6), agrees fairly closely in the dimensions
and shape of the centrum to the corresponding dorsal
vertebra of USNM 23494. The other, now regarded as the
fifth dorsal (ANSP 12769; pl. 46, fig. 5), however, belongs
in the dorsal series of another Calvert cetothere, since it
has a wide dorsoventrally compressed subcordate anterior
end on the centrum and is quite obviously different in
profile. Another vertebra, the eighth dorsal (pl. 46, fig. 4),
in this collection of ten, is smaller than its counterpart in
the USNM 23494 skeleton. At least two different cetotheres
are thus represented among the dorsals designated by
Cope as type vertebrae. All of these vertebrae possess mere
basal remnants of their processes and they do not exhibit
other features on which a precise characterization may be
based. The identification of the original type vertebrae of
M. expansa is further complicated by the association under
one catalog number (ANSP 12769) of 28 or more vertebrae,
in part at least originally included among the many verte-
brae on which Cope (1868d, p. 191) based Eschrichtius
pusillus, a somewhat larger mysticete. No justification
exists either on the basis of the supposed diagnostic charac-
ters listed by Cope or on the shape, characteristics and
dimensions of any of the vertebrae then available to him
for referring Megaptera expansa either to Megaptera, Eschrich-
tius, Siphonocetus, or Cetotherium. The species Megaptera
expansa is, therefore, held to be indeterminable and to be
ignored henceforth.
MESOCETUS Van Beneden
Mesocetus Van Beneden, 1880, Bull. Acad. roy. Sci., Lettres et
Beaux-Arts Belgique, Bruxelles, ser. 2, vol. 50, no. 7, p. 22.
Type Species: Mesocetus longirostris Van Beneden. (Type
fixed by Hay, Bull. no. 179 U.S. Geol. Surv., Dept. In-
terior, 1902, p. 600).
Diagnosis: Van Beneden’s rather brief generic diagnosis
of Mesocetus (1880, p. 22) is limited to the relations of bones
that comprise the top of the cranium—the well-developed
parietals and the long space between the [apex of] supra-
occipital and the frontals. Subsequently from Croatia
[Yugoslavia] under the generic name Mesocetus, Van
Beneden did describe and illustrate as M. agrami a posterior
end of a left mandible (1884, pl. 2, fig. 10) and also a
basicranium with attached tympanic bulla and periotic.
Comments in this memoir apparently led Cope (1895a, p.
153) to state that Van Beneden established Mesocetus for
mysticetes that resemble odontocetes in having the trans-
verse widening of the condyle situated at the middle of the
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 5
relatively thin and laterally compressed posterior end of |
the mandible. The articular condyle is thus situated below
the dorsal rim of the posterior portion of the ramus behind
the coronoid process. Van Beneden observes that the
condyle of M. agrami is flattened and widened with pro-
jecting lateral edges, but is not set off from the ramus
like the head of a femur, and is adapted to articulate almost
vertically with the glenoid surface of the squamosal. As
a result of his own observations, Van Beneden (1884, p.
18) attached great importance to the condyle for the estab-
lishment of the generic sections among mysticetes.
MESOCETUS SIPHUNCULUS Cope
Mesocetus siphunculus Cope, 1895a, Proc. American Philos. Soc.,
Philadelphia, vol. 34, no. 147, p. 153.
Type Specimen: AMNH 22665. Anterior portion of
right mandible and its detached condyle; coronoid process
and the portion of the ramus between coronoid process
and condyle destroyed. Collector, E. D. Cope; April 1895.
Type Locality: Pamunkey River, probably near Hanover,
Hanover County, Virginia. Associated with a turtle
(Syllomus crispatus Cope), vertebrae of at least four Calvert
odontocetes and the anterior ends of two mandibles of a
smaller cetothere. Marl,? Calvert formation, middle
Miocene.
Referred specimens: (1) Left humerus, essentially com-
plete, and (2) the first dorsal and centra of two other
anterior and one middle dorsal vertebrae (pl. 47); Pa-
munkey River, Hanover County, Virginia, AMNH 22669,
coll. E. D. Cope, April 1895.
Diagnosis: Cope (1895a, p. 153) states that the mandib-
ular ramus ‘‘has no large dental canal, but it is almost
entirely filled with spongy bone of moderate coarseness.
The gingival canals united into a single tube, which is not
larger than one of the external gingival canals, and which
runs about opposite to them or a little distance below the
superior edge. In this disposition of the canals Mesocetus
differs from any of the genera of Mystacoceti referred to
in the preceding pages.” This mandible was fractured while
being excavated and subsequently repaired under Cope’s
supervision. It is not now possible to ascertain the actual
internal structure. Close scrutiny, however, of similar
mandibles confirms the belief that the type mandible of
Mesocetus siphunculus does not differ appreciably from the
internal canal arrangement described under Siphonocetus
priscus.
2 A sample of matrix attached to the type specimen was submitted
for heavy mineral analysis to Dr. Lincoln Dryden, Bryn Mawr
College. Since the percentage of staurolite exceeded that of tourmaline
and zircon, Dr. Dryden was inclined to believe that Cope collected
this fossil material from a horizon near the base of the Calvert forma-
tion, possibly a foot or so above the contact with the Eocene.
MIOCENE CALVERT MYSTICETES 119
Ficure 49.—Views of right mandible, AMNH 22665, of Mesocetus siphunculus Cope: a, external view; 6, dorsal view. Abbrs.:cm., condyle;
cor., coronoid process; f.g., gingival foramen; f.m., mental foramen.
Mandible
The type right mandible of Mesocetus siphunculus
(fig. 49a) represents a larger cetothere than the left man-
dible of Isocetus depauwit (Van Beneden, 1886, pl. 70;
length, 1128 mm.) whose vertical diameter at the distal
end is 84 mm. in contrast to 99.5 mm. for the Virginia
Calvert species, and 76 mm. 440 mm. behind the anterior
end versus 89 mm. 500 mm. behind the anterior end for
M. siphunculus. The vertebrae associated with the type
mandible of J. depauwii have the epiphyses loose or
detached from the centra, indicating physical immaturity.
The type mandible of M. siphunculus is also smaller than
that of Mesocetus pinguis (Van Beneden, 1886, pl. 44, fig. 10;
length, 1642 mm.) and is intermediate in size between the
latter and Isocetus depauwi. If not identical with I. depauwi
it appears rather closely allied to this Belgian species.
Both Mf. stphunculus and I. depauwit possess much narrower
condyles on the mandibles than M. pinguis. The transverse
diameters of the mandibular condyles are respectively:
61.5 mm. for M. siphunculus, 55 mm. for I. depauwii, and 96.5
mm. for M. pinguis. The shape of the condyle of M. sphun-
culus (pl. 47, fig. 2) is also somewhat similar to that of
T. depauwi (Van Beneden, 1886, pl. 70, fig. 8). In making
any comparison, it should be noted that the angle of the
mandible is broken off below the level of the groove for
the internal pterygoid muscle. The internal gingival
foramina are not clearly recognizable on the mandible of
T. depauwit (Van Beneden, 1886, pl. 70, fig. 1); they are
situated normally on the internal face of the mandible
of M. siphunculus (fig. 49b).
Although Cope states that the type mandible of M.
siphunculus is not strongly convex either on the internal or
external side, his diagrammatic figure (Cope, 1896, pl. 12,
fig. 6) does not bear this out. The convexity of the external
face does, however, exceed that of the internal.
Measurements (in mm.) of the type left mandible are
as follows: greatest length in straight line when complete,
estimated, 1200+ ; greatest length as preserved in a straight
line, 1128; distance from anterior end to center of coronoid
process along outside curvature, 1040; vertical diameter
100 mm. behind anterior end of ramus, 99.5; transverse
diameter at same point, 32; vertical diamter 700 mm.
behind anterior end of ramus, 89.5; transverse diameter
at same point, 58; greatest vertical diameter of hinder end
including condyle, 115; greatest transverse diameter of
condyle, 61.5.
Humerus
Another skeletal element mentioned by Cope (1895a,
p. 154) in his description of Mesocetus siphunculus, but not
definitely referred to it, is a left humerus (AMNH 22669)
which was found near the excavated anterior ends of two
right mandibles (lengths, respectively, 167 and 225 mm.)
which represent a somewhat smaller cetothere than the
type mandible, since the vertical diameter near the anterior
end of the longest specimen is 56 mm. This humerus has
been split lengthwise but subsequently repaired and the
greater tuberosity is eroded; both epiphyses are fused with
the shaft. Cope remarks (1895, p. 154) that “the tuberosity
is not produced beyond the head, and the olecranar facet
is not distinguished by an angle from the remainder of the
ulnar facet.”? Although worn, the conformation of the greater
tuberosity does not differ materially from other larger
and smaller Calvert humeri. The shape of the ulnar facet
is not unusual. The articular surface of the horizontal
portion merges with the vertical portion of the ulnar facet
in a gradual curve. The features cited by Cope would not
be regarded as diagnostic for Calvert cetotheres. Compari-
son cannot be made with Jsocetus depauwi as the Belgian
humerus was not illustrated by Van Beneden. Whether or
not this humerus really belongs to M. s¢phunculus is uncertain.
120
This left humerus (fig. 50a) has a large, convex head,
whose greatest diameter is 107 mm. As in other Calvert
cetotheres, the head is placed obliquely on the shaft, facing
outward and backward. Between the head and the radial
or greater tuberosity there is a shallow groove on the
external face that limits the articular surface of the former
anteriorly. The small rugose area on the external face
below this groove may have served for the attachment of
M. mastohumeralis. There is also a large central swelling
or knob at the proximal end of the internal face (fig. 50b).
The rugose internal surface of the greater tuberosity pre-
sumably served as the area for insertion of M. infraspinatus
and M. subdeltoideus, and the protruding knob below on
the anterointernal angle for a portion of the insertion of
M. deltoideus.
Ficure 50.—Views of left humerus, AMNH 22669, of Mesocetus
siphunculus Cope: a, external view; 6, internal view; c, distal
view. Abbrs.: h, head; r.f., radial facet; r.t., radial or greater
tuberosity; u-.f., ulnar facet.
Since the shaft was split lengthwise the median rugose
area on the outer surface shown on the line drawing (fig.
50a) may have been over emphasized. This median rugose
area may have served for attachment of the short head of
M. triceps or M. teres major. A right humerus (USNM
23708) of similar dimensions from the Calvert formation,
14 miles south of Plum Point, Calvert County, Maryland,
lacks this rugose area.
The thick shaft is slightly constricted near the middle of
its length, but is flattened exterointernally toward its
distal end. At the transversely compressed distal end of the
shaft (fig. 50c) the ulnar facet is approximately the same
width as the radial facet and is extended upward on the
posterior face of the shaft for a short distance. A low trans-
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 5
verse crest separates the ulnar facet from the shorter radial _
facet.
Measurements (in mm.) of the humeri are as follows:
AMNH USNM
22668 23708
Left Right
Greatest length of humerus 233.5 229
Greatest anteroposterior diameter of 128 123
proximal end
Greatest anteroposterior diameter of 107 104
articular head
Greatest exterointernal (transverse) di- 95 91
ameter of articular head
Least anteroposterior diameter of shaft 88 87
Least exterointernal (transverse) di- la}. 5) 56
ameter of shaft
Greatest anteroposterior diameter of 107.5 105
distal end
Greatest exterointernal (transverse) di- 56.8 56
ameter of distal end
Greatest anteroposterior diameter of 57 55
radial facet
Greatest anteroposterior diameter of
ulnar facet (in a straight line)
69.5 65
Vertebra
DorsAL VERTEBRA.—Cope (1895a, p. 154) assigned pro-
visionally to this species a “‘first dorsal’? vertebra (AMNH
22669) ‘found in immediate contact with the posterior
part of the ramus,” that is, with the type specimen. The
measurements published by Cope (1895a, p. 155) for the
‘first dorsal” are somewhat at variance with those of the
sole anterior dorsal (pl. 47, fig. 1), which lacks both epiphy-
ses, now associated with the type mandible. These measure-
ments (in mm.) are as follows: anteroposterior diameter
of centrum, 35; vertical diameter of centrum anteriorly,
56.5; transverse diameter of centrum anteriorly across
demifacets, 87.5; greatest vertical diameter of neural canal
anteriorly, 30.5; greatest transverse diameter of neural
canal anteriorly, 49; and distance between outer ends of
diapophyses, 159.5.
Consecutive series of dorsal vertebrae of at least three
different Calvert cetotheres, ranging in size from the small
Parietobalaena palmeri to the larger Pelocetus calvertensis are
represented in the United States National Museum verte-
brate paleontological collections. Structurally all the dorsal
series of these Calvert cetotheres conform to one basic
pattern. On each side of the anterior dorsals the pedicle of
the neural arch is coalesced basally with the corresponding
portion of the diapophysis; this combined structure is
transversely widened and projects outward as much from
MIOCENE CALVERT MYSTICETES
the lateral as from the dorsal surface of the centrum on the
first, second, and third, and, to a lesser extent, on the
fourth dorsal. With the exception of the width (49 mm.)
of the neural canal anteriorly, the vertebra (pl. 47, fig. 1)
regarded by Cope as the “‘first dorsal’ does not conform
either in location or construction of the pedicle of the
neural arch with either one of the first three dorsals, and
the greatest distance between the outer margins of the
postzygapophyses (55.5 mm.) would preclude allocation
to any dorsal behind the fourth. The separation of the
postzygapophyses is abruptly diminished behind the
fourth dorsal.
As regards dimensions and essential characteristics, this
dorsal vertebra resembles more closely the fourth dorsal of
a smaller cetothere whose mandibles correspond in size
with the anterior ends of the two mandibles mentioned
previously. Rather frequently in these Calvert marls,
bones of more than one individual are found associated in
close proximity and at the same stratigraphic level.
Our present knowledge of the range of variation of skeletal
elements of younger than physically mature fossil mysticetes
does not permit a diagnostic generic characterization of
this species which is based solely on one mandible, a
doubtfully allocated humerus, and a dorsal vertebra. There
is a strong probability, however, that this Calvert cetothere
should be assigned to Jsocetus rather than Mesocetus and
tentatively bear the name Jsocetus siphunculus (Cope).
METOPOCETUS Cope
Metopocetus Cope, 1896, Proc. American Philos. Soc., Philadelphia,
vol. 35, no. 151, p. 141.
Type Species: Metopocetus durinasus Cope.
Diagnosis: Backward thrust of rostrum has carried median
rostral elements (ascending processes of premaxillaries and
the nasals) backward beyond level of center of orbit; ex-
posure of frontals on median interorbital region eliminated;
thin anterior process of parietal, which overrides basal
portion of supraorbital process of frontal, extended forward
beyond level of hinder ends of median rostral elements;
attenuated posterior end of each ascending process of pre-
maxillary mortised into median interorbital portion of
underlying frontal, in close contact if not fused with cor-
responding nasal, and in contact laterally with the narrow
projecting ledge contributed by the outward bent dorsal
border of thin anterior process of parietal; nasal bones
fused or coossified along median longitudinal line of con-
tact, but each is elongated and attenuated toward posterior
end; intertemporal region narrow.
The diagnostic characters of the genus Metopocetus were
described in the key by Cope (1896, p. 141) as follows:
121
““A temporal ridge; maxillaries little produced posteriorly;
nasals not produced beyond frontal, coossified with the
frontal and with each other.” In the preceding descriptive
text Cope cites other characters that also require attention,
including lateral occipital (lambdoidal) crests continuous
with anterior temporal crests which diverge forward.
“Frontal bone elongate, not covered posteriorly by the
maxillary, coossified with the nasals. Nasals short, coossified
with each other, not projecting anterior to frontals.”’ Cope’s
interpretation of the relationships of these bones will be
reviewed under the diagnosis for the type species.
METOPOCETUS DURINASUS Cope
Metopocetus durinasus Cope, 1896, Proc. American Philos. Soc.,
Philadelphia, vol. 15, no. 151, p. 141.
Type Specimen: USNM 8518. An incomplete cranium
with right periotic zn sttu. Deposited by Goucher College,
Baltimore, in Division of Vertebrate Paleontology, U.S.
National Museum. Collector, Arthur Bibbins.
Type Locality: Nomini Cliffs near mouth of Potomac
River, Westmoreland County, Virginia. Marl, Calvert for-
mation, middle Miocene.
Diagnosis: In reviewing the proposed generic characters,
the presumed ankylosis of the frontal and nasal bones may
first be given consideration. Winge (1909, pp. 27-28) very
properly makes the point that this character is an indication
of advanced age rather than a generic distinction. This is
quite true, but it should be noted that such ankylosis appears
to be rather unusual among mysticetes, at least, so far as
can be observed among specimens in museum collections or
those illustrated by various authors. While this peculiarity
may not be of much importance, if correlated with others
the tendency to ankylosis might possibly be regarded as a
convenient distinguishing feature.
Should there exist any doubt regarding the validity of
Cope’s interpretations, a critical review of the cranial archi-
tecture of other Miocene mysticetes that either resemble or
are Closely related to Metopocetus should serve a usetul
purpose.
Skull
The supposed relations of the frontals and maxillaries
are of somewhat greater significance than the temporal
ridge and the lateral occipital crests. If the actual relation-
ships of these bones were as Cope interpreted them, Meto-
pocetus would be quite different from other genera of
whalebone whales. By referring to Cope’s illustration
(1896, pl. 11, fig. 3) of this type cranium, one will note
that the anterior borders of the broken off bones, labeled
as frontals, were considered by Cope to represent the
122 UNITED STATES NATIONAL MUSEUM BULLETIN 247
sutural contacts with the hinder ends of the premaxillaries
and maxillaries and, accordingly, that these two last
mentioned bones terminated opposite the anterior ends of the
nasal bones. The actual relations of these bones are most
certainly quite different.
Two alternative interpretations of the relations of the
posterior ends of the premaxillaries and maxillaries may be
considered. Assuming that the contact margins of each of
the normally narrow attenuated posterior ends of the pre-
maxillaries have been obliterated by coalescence with the
corresponding nasal, the narrowed posterior end of each
maxillary has then been thrust backward beyond the level
of the posterior ends of the nasals.
PART 5
The other assumption would be that the posterior ends
of the premaxillaries have been broken off fortuitously
opposite or barely posterior to the level of the anterior
ends of the nasals. Breakage is clearly evident when one
examines under a binocular microscope the eroded and
broken bone surfaces. Each underlying frontal is then over-
laid by the ascending process of the corresponding pre-
maxillary and its posterior extremity extends backward to
the short intertemporal region and almost to the vertex.
The backward overriding of the frontal by the nasal and
premaxillary in a similar manner may also be observed on
the cranium of Mesocetus longirostris (Van Beneden, 1886, pl.
34, fig. 1).
Ficure 51.—Dorsal view of skull, USNM 8518, of Metopocetus durinasus Cope. Abbrs.: Al., alisphenoid; c., occipital condyle; Ex.oc.,
exoccipital; Na., nasal; Pa., parietal; pgl., postglenoid process; Pmx., premaxillary; S.oc., supraoccipital; Sq., squamosal.
MIOCENE CALVERT MYSTICETES
On a Mesocetus skull (No. 5069) in the Zoological Museum
at Amsterdam, The Netherlands, dredged up at a depth of
20 meters at Herenthals, Belgium, the nasals, strongly
attenuated posteriorly but not co-ossified, are wedged in
between but do not extend backward beyond the ascending
hinder ends of the premaxillaries; these hinder portions of
the premaxillaries are broken off at or just beyond the
anterior ends of the nasals; and the ascending posterior end
of each maxillary overlies the supraorbital process of the
frontal alongside the hinder end of the premaxillary but
does not extend as far backward. On the type skull of
M. durinasus (fig. 51; USNM 8518) the supraorbital process
of the frontal on each side, however, is broken off behind
the posterior end of the maxillary and anterior to the hinder
end of the ascending process of the premaxillary. A similar
condition exists on the type skull of Mesocetus longirostris
(MHNB 39; Van Beneden, 1886, pl. 34, fig. 1).
The two nasal bones of M. durinasus are fused longitudi-
nally along the median line of contact, strongly attenuated
posteriorly, wedged in externally between the posterior
ascending ends of the premaxillaries, and are nearly com-
plete anteriorly except for a narrow strip broken off dorsally.
The posterior ascending portion of each premaxillary on
each of these three fossil mysticete skulls is broader than
normally on Miocene skulls and the backward thrust is
restricted by the elevated temporal crest or ridge.
The skull of Metopocetus durinasus is of moderate size like
those of Belgian fossil mysticetes assigned to the genera
**Heterocetus,’ Mesocetus, ‘‘Idiocetus,’ and Tsocetus. The
cranium is larger than those of ‘‘Heterocetus”? brevifrons and
“HI.” sprangu, and Mesocetus latifrons; smaller than Mesocetus
pinguis and somewhat smaller than either Mesocetus longi-
rostris (Van Beneden, 1886, pl. 34, fig. 1) or ‘‘Idiocetus’
laxatus (Van Beneden, 1886, pls. 57—58).
The apical portion of the supraoccipital shield is atten-
uated on the skulls of Metopocetus durinasus (fig. 51) and
M. vandelli (Kellogg, 1940, pl. 1), more abruptly so than
on Cetotherium rathki (Brandt, 1873, pl. 1, fig. 1), but all
three types are quite unlike the more rounded and some-
what broader apical portion of the supraoccipital shield
of Mesocetus longirostris (Van Beneden, 1886, pl. 34, fig. 1).
The nasal bones on the skull of Cetotherium rathki are not
extended forward beyond the level of the preorbital angles
of the supraorbital processes of the frontals; these bones
are, however, noticeably extended forward beyond these
angles on the skull of Metopocetus vandelli and possibly also
on the skull of AZ. durinasus.
At the time when the type skull was described by Cope
and later studied by True (1907) at the Woman’s College
(subsequently named Goucher College), Baltimore, Mary-
land, the left exoccipital, the left squamosal, and the right
zygomatic process had been broken off from the strongly
ossified cranium. Both occipital condyles and the adjoining
123
basicranium, as far forward as the nasal choanae, were,
however, attached to the cranium; these bones are now
missing. Prominent knoblike lateral descending pro-
tuberances were present on each side of the now lost
basioccipital.
The extent of the overriding of the cranial bones in the
interorbital region by the median rostral bones suggests
that the remodeling of the skull had advanced farther in
Metopocetus durinasus than in Mesocetus longirostris.
Measurements (in mm.) of skull of USNM 8518 are as
follows:
Transverse diameter of skull across outer surfaces of 590+
zygomatic processes, estimated
Transverse diameter of skull between outer margins of
exoccipitals, estimated
Transverse distance between outer surfaces of occipital 150
406+
condyles
Vertical diameter of occipital condyle 95
Transverse diameter of foramen magnum 65
Greatest length of right nasal bone 155
Combined width of nasal bones, anteriorly 60
Distance from anterior end of nasal to articular surface of 450
occipital condyle
Anteroposterior diameter of zygomatic process ventrally 115
In the above table, measurements of the occipital condyles,
foramen magnum, zygomatic process, and the distance
from occipital condyle to anterior end of nasal are those of
either Cope or True, which were taken prior to subsequent
breakage and loss of portions of the type cranium.
Periotic
The lateral protuberances on the basioccipital are much
less strongly developed and the posterior process of the
periotic of M. durinasus is quite differently shaped from
that of “‘Jdtocetus” laxatus (Van Beneden, 1886, pl. 54, figs.
3-4) which has a slender, elongated posterior process and a
very short anterior process. The posterior process of M.
durinasus, which is lodged between the postglenoid process
of the squamosal and the exoccipital, has an unusually
deep lengthwise groove for the facial nerve, which imparts
a U-shaped outline to the distal end of this process, and in
this respect exhibits a rather close resemblance to that of
Mesocetus longirostris (Van Beneden, 1886, pl. 36, figs. 4-6).
This Belgian left periotic (MNHB 1539) is characterized by
the wide interoexternal groove for the facial nerve, which
increases in width distally and imperts a spatulate appear-
ance to the posterior process when viewed from the ventral
side. From a posterior view, however, the posterior process
is somewhat compressed anteroposteriorly and strongly
attenuated toward the distal end. The length of this process
is at least 95 mm. in contrast to 75 mm. for that of M.
durinasus.
124
In addition to the resemblances observed in the posterior
process, the right periotic of Metopocetus durinasus appears to
approach Mesocetus longirostris in other characters as well.
The pars cochlearis (pl. 48, fig. 3) of this Calvert cetothere is
distinctly compressed in a dorsoventral direction and its
ventral surface although convex is much less inflated than
the same portion of the periotic of Parietobalaena palmeri
(Kellogg, 1924, pl. 5, figs. 1-4). In this structural modifica-
tion the periotic of M. durinasus seems to agree more closely
with the periotic of Mesocetus longirostris than with those of
other Belgian species.
The anterior process of M. durinasus is strongly compressed
from side to side; the pars labyrinthica is rounded and nodular.
From a ventral or tympanic view, the fenestra ovalis is con-
cealed by the overhanging external face of the pars
cochlearis. The shallow concavity for the reception of the
head of the malleus is relatively large and is located be-
tween the fused base of the anterior pedicle of the bulla
on the anterior process and the epitympanic opening of
the Fallopian aqueduct.
Below the inward projecting wide but thin continuous
rim of the circular internal acoustic meatus and the orifice
of the Fallopian aqueduct, the cerebral face of the pars
labyrinthica (pl. 48, fig. 4) is deeply depressed or excavated.
This overhanging rim projects inward as much as 12 mm.
beyond the very small orifice of the vestibular aqueduct
and almost at a right angle to the cerebral face of the pars
labyrinthica. The orifice of the cochlear aqueduct is actually
slightly larger than the orifice of the vestibular aqueduct
which opens into an unusually short slitlike depression.
The fenestra rotunda is almost as large as the internal
acoustic meatus. A broad but short concave surface com-
mencing above the posterior rim of the stapedial fossa and
above the projecting shelf behind the fenestra rotunda
extends across the posterior face of the pars cochlearis to the
inner cerebral surface of the periotic. Van Beneden did not
illustrate the internal cerebral face of the periotic of
Mesocetus longirostris.
Measurements (in mm.) of periotic of M. durinasus
(USNM 8518) and M. longirostris (Van Beneden, 1886, pl.
36; fig. 4-5, MNHB 1539) are as follows:
USNM MNHB
8518, 1539,
Type, Right Left
Tip of anterior process to tip of posterior 135 145
process
Epitympanic orifice of Fallopian aque- 51 48 .3
duct to tip of anterior process
Fenestra rotunda to tip of anterior process 59 61.8
Fenestra rotunda to tip of posterior process 89 103.3
Tympanic face of pars cochlearis to dorsal 44 46.5
face of pars labyrinthica
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 65
USNM MNHB
8518, 1539,
Type, Right Left
External face of pars labyrinthica to cerebral 32 36.5
face of pars cochlearis below internal
acoustic meatus
Greatest length ventral face of pars 4] =
cochlearis
Auditory Ossicles
Mat.eus.—The anteroposteriorly compressed slender stalk
like anterior process is broken off above its point of ankylosis
with the body of the right malleus. The two facets on the
head of the malleus (USNM 8518; pl. 48, fig. 5) that
articulate with the incus have the same shape and a similar
position as the corresponding facets of Balaenoptera borealis.
The nearly vertical hemicircular facet is above and sepa-
rated by a groove from the somewhat horizontal smaller
facet. At the internal end of the processus muscularis the
manubrium is a short blunt nosed tubercle to which the
ligamentary process of the tympanic membrane presumably
was attached. The small, deep, circular pit on the anterior
face near the internal end of the head of the malleus is
situated in the usual area of attachment of the tensor
tympani tendon. The head of this right malleus measures
15.5 mm. in length and 10.5 mm. in width. This malleus
is not only larger than USNM 15575, but the internal end
of the head is blunted and not attenuated.
Incus.—Two distinct facets on the body of the incus
(USNM 8518) articulate with corresponding surfaces on
the malleus, the largest of which (pl. 48, fig. 1) is shallowly
concave, subcrescentic in outline and occupies the base of
the body; it is separated from the smaller and more deeply
concave facet on the internal side by a sharp-edged crest.
The body of this right incus is rather bulbous in contrast
to the short, bent outward crus longum, which has on the
external face of its apex an ovoidal facet for articulation
with the head of the stapes. The short crus breve is conical;
its attenuated apical end rests in the minute fossa incudis.
From the apex of the crus longum to the base of the body,
the incus measures 9.5 mm., and the greatest diameter of
the base is 6.3 mm.
Srapes.—The right stapes (USNM 8518; pl. 48, fig. 2)
of this Calvert cetothere resembles rather closely the same
inner ear bone of Balaenoptera acutorostrata (Doran, 1878,
pl. 62, fig. 31). The intercrural aperture is small and con-
nects the ovoidal concavities of the opposite sides. The foot-
plate is closely fitted to the circumference of the fenestra
ovalis and apparently permitted none or very limited side
to side movement when in position. Nevertheless, only two
of the 27 Calvert periotics examined retained the stapes in
its normal position; it had been dislodged from the fenestra
ovalis and lost on 24. A small scar on the posterointernal
angle, which presumably marks the area of attachment of
MIOCENE CALVERT MYSTICETES 125
the tendon of the stapedial muscle, is less protuberant than
in B. acutorostrata. The facet on the head of the stapes serves
as the contact with the corresponding facet on the crus
longum of the incus. The greatest length of this right stapes
is 7.3 mm., and the greatest diameter of its footplate is 5 mm.
Vertebra
AtTLAs.— ‘From the same locality and collection as the
type skull’? Case (1904, pl. 18, figs. 2a, 2b) figures a slightly
eroded atlas (USNM 8518) whose dimensions correspond
fairly closely to the greatest distance between the outside
margins of the occipital condyles (150 mm.). The greatest
distance between the outside margins of the anterior artic-
lar facets of this atlas is 166 mm., and the dorsoventral
diameter of the right articular facet is 107 mm. The dimen-
sions of this atlas are similar to those of Mesocetus longzrostris
(Van Beneden, 1886, p. 47), except that it appears to be
thinner, though this may possibly be the result of erosion
on the posterior articular facets.
During the 70 years that have elapsed since the description
of this type specimen, no other specimen that even remotely
resembles this type of cranial architecture has either been
added to the national collections or has been recognized
among the many portions of skulls submitted for identifica-
tion by local collectors. The construction of the skull and
the peculiarities of the periotic, however, suggest a rather
close affinity if not identity with the genus Mesocetus.
SIPHONOCETUS Cope
Siphonocetus Cope, 1895a, Proc. American Philos. Soc., Phil-
adelphia, vol. 34, no. 147, p. 140.
Type Species: Balaena prisca Leidy.
Diagnosis: Alveolar groove and dental [mandibular]
canal distinct; alveolar groove roofed over and perforate.
During the sequential developmental history of the mys-
ticete mandible, failure of teeth to develop, according to
Cope (1895a, p. 139), “‘would be accompanied by the loss
of the interalveolar walls or septa, leaving the dental
[alveolar] groove continuous and separate from the dental
[mandibular] canal.”
By having the alveolar “‘groove roofed over and distinct
from the dental canal” this genus according to Cope
represents a transitional stage following the loss of teeth
and elimination of the intervening osseous septa between
alveoli which would leave a continuous open groove
separate from the dental (mandibular) canal. The genus
Siphonocetus thus reputably had the dental (alveolar) groove
‘‘roofed over by the ossification of the gum and distinct
from the dental [mandibular] canal.” Gingival passages
and foramina were present.
Winge (1909, p. 25; True, 1912, pp. 5-6) was certain
“that Cope’s interpretation of the canals in the lower jaw is
incorrect,” and pointed out that the furrow on the dorsal
face of the mandible in which the fetal rudimentary teeth
are lodged is closed, as in the adult finback, by growth
of bony tissue. Furthermore, the mandibular canal through
which the mandibular branch of the trigeminal nerve
and associated blood vessels extend forward, is here
described as being divided into an upper and lower passage
or aqueduct in contrast to its usual undivided condition.
From the upper aqueduct (the alveolar groove of Cope)
branch channels on each side lead to the internal nutrient
or gingival foramina and the external mental foramina.
Several Calvert cetothere mandibles had been broken
transversely prior to excavation. Critical examination of
these cross sections revealed that the position of the internal
longitudinal mandibular canal as well as the distribution
of the aqueducts leading to the external mental and the
internal nutrient foramina correspond to the general
arrangement in the Recent balaenopterine mandible. Ten
interior dental arteries (branches of the mandibular artery)
and their accompanying veins as well as multiple nerves
were observed by Walmsley (1938, p. 143, fig. 35) in the
mandibular canal of an adult finback (Balaenoptera physalus)
cut transversely at about half way of its length.
SIPHONOCETUS PRISCUS Leidy
Balaena prisca Leidy, 1852, Proc. Acad. Nat. Sci. Philadelphia,
vol. 5, no. 12, p. 308. (Preoccupied by Balaena prisca Nilsson,
1847, Skandinavisk Fauna, Lund, ed. 1, vol. 1 (Daggdjuren),
p. 643. Fossil Fenhval. Type locality, sand near Ystad, Sweden,
in 1722. Skull, atlas, dorsal vertebra and scapula.)
Balaenoptera prisca Cope, 1868b, Proc. Acad. Nat. Sci. Phila-
delphia, vol. 19, no. 4, pp. 144, 147.
Eschrichtius priscus Cope, 1869, Proc. Acad. Nat. Sci. Philadelphia,
vol. 21, no. 11, p. 11.
Cetotherium priscum Cope, 1890, American Nat., vol. 24, no. 283, p.
616. (Not, Cetotherium priscum Brandt, 1842, Bull. Acad. Imp.
Sci. St. Petersburg cl. phys.-math., vol. 1, nos. 10-12, p. 148.)
Siphonocetus priscus Cope, 1895a, Proc. American Philos. Soc.
Philadelphia, vol. 34, no. 147, pp. 140, 141, 151, pl. 6, fig. 3.
Type Specimen: ANSP 12915. Fragment near middle of
left mandible, presented by Robert H. Nash.
Type Locality: Westmoreland County, Virginia, Mio-
cene.
Diagnosis: On October 21, 1851, two vertebrae and a
piece of a mandible of a fossil cetacean [= Balaena prisca
Leidy] as well as two vertebrae and two teeth of a saurian
[=Crocodilus antiquus Leidy] from Westmoreland County,
Virginia, were listed among the recent accessions to the
Academy of Natural Sciences of Philadelphia as having
been presented by Robert H. Nash (Proc. Acad. Nat. Sci.
Philadelphia, vol. 5, 1851, p. 298). The fragment of the
left mandible and a rather large caudal vertebra, which
obviously did not belong to such a small setothere, formed
126
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 5
se
a
NG,
LETTS =
the basis for Leidy’s Balaena prisca. Leidy apparently did
not originally publish precise measurements of the mandib-
ular fragment (fig. 52) as will be noted from the appended
measurements, but merely states that its length was 14
inches, vertical diameter 3 inches, and transverse diameter
2 inches. Subsequently, Leidy (1869, p. 442) published the
following measurements of this mandibular fragment:
Depth posteriorly, 34 lines [=71.9 mm.], anteriorly, 34
lines [=71.9 mm.]; thickness posteriorly, 24 lines [=50.8
mim.], anteriorly, 22 lines [=46.5 mm.]. Confirmatory
measurements of the type mandible (ANSP 12915) are as
follows: Maximum length, 375 mm.; vertical diameter at
level of anterior mental foramen, 72 mm.; maximum
transverse diameter at same point, 45.5; maximum vertical
diameter 175 mm. behind anteriormost mental foramen,
72.5 mm.; maximum transverse diameter at same point,
50 mm. Six small internal nutrient (gingival) foramina in
an interval of 190 mm.; five external mental foramina in
an interval of 170 mm.
Km.
Ficure 52.—Left mandible (type), ANSP 12915, of Siphonocetus priscus (Leidy): a, external view; 6, cross section; c, dorsal view. Abbrs.:
c.a., alveolar or mandibular canal; f.g., alveolar or gingival foramen; f.m., mental foramen.
Cope (1869, p. 10), the same year, however, characterized
the type mandible as follows: “upper edge broad, with
outer series of foramina, and meeting inner edge at a right
angle, which is the highest line, and with inner series of
foramina just below it; most convex externally; large.”
A label in the handwriting of Cope, now attached to this
type mandible fragment, reads as follows: “‘Siphonocetus
priscus, Balaena prisca Leidy. Neocene. City Point, Va.
Rich’d Eppes, M.D.” It is quite likely that this label was
written in 1895. In that year Cope (1895a, p. 151) wrote
that “Dr. Eppes discovered in the year 1854 the specimen
which became the type of the S. priscus of Leidy.”? Cope
obviously was mistaken both as to the date of collection
and the collector, and also the locality, and some way
confused the two mandibles that Leidy described at the
meeting of the Academy of Natural Sciences of Philadelphia
held on November 11, 1851. At that time, Leidy described
Balaena prisca and Balaena palaeatlantica. The type of Balaena
palaeatlantica was collected in 1851 by Dr. Richard Eppes
MIOCENE CALVERT MYSTICETES
on the south bank of the James River near City Point,
Prince George County, Virginia, and presented by him to
Professor W. E. Horner.
Cope (1895a, p. 140) made Balaena prisca the genotype
of his new genus Stphonocetus which, with some other species,
he established in part on theoretical grounds to meet with
his interpretation of the relationships of the dental (man-
dibular) canal and the alveolar groove in different man-
dibles of fossil mysticetes. Cope (1895a, p. 139) considered
that in the course of evolutionary development, after the
lower teeth were lost, the alveolar septa were absorbed,
leaving a continuous alveolar groove separated from the
dental (mandibular) canal. He believed that in some
instances this alveolar groove remained distinct from the
dental canal and was roofed over by bone, while in others
it united with the dental canal, and that this composite
“‘singivodental”” canal was completely or partially roofed
over by bone in some forms, but left open in others.
Those fossil mysticetes that have mandibles in which the
alveolar groove and dental canal remained distinct or
separate, but with the dorsal alveolar groove roofed over
and perforated, Cope called Siphonocetus. Those in which
the alveolar groove and dental canal were united into one
gingivodental canal which was partially roofed over and
with gingival passages and foramina on one side, he called
Tretulias, while those which had the composite gingivo-
dental canal open and no gingival passages, he called
Ulias. Cope characterized the genus Cetotherium Brandt as
having the alveolar groove and the dental canal combined
and the resulting single gingivodental canal completely
roofed over and perforated.
In summary the generic criteria proposed by Cope for
the characterization of the genus Siphonocetus, which were
based largely on theoretical considerations, have not been
confirmed by examination of a number of Calvert mandibles
of comparable dimensions and shape and are now regarded
as erroneous and invalid. The asserted division of the
mandibular canal into an upper and lower passageway by
the intervening bone does not distinguish the type mandible
of Balaena prisca, the type species of Siphonocetus, from that
of Cetotherium rathki, the type species of that genus. Further-
more, Balaena prisca Leidy, 1852, is antedated by Balaena
prisca Nilsson, 1847. Leidy’s type mandibular fragment
has not been proven distinguishable from mandibles of
other Calvert cetotheres and is, therefore, unidentifiable.
In the absence of a recognizable osteological basis, the
generic name Szphonocetus will not be employed in this
review.
Caudal Vertebra
The caudal vertebra, which Leidy originally described
as found associated with the mandibular fragment, and
which he regarded as belonging to the same species, appears
127
to be far too large as compared with the dimensions of the
mandible to be referable to the same mysticete. As it is
without the neural spine, and has never been illustrated,
this caudal hardly merits further consideration. Leidy’s
measurements (1869, p. 442) of this caudal vertebra were
as follows: Length of centrum, inferiorly, 67 lines [=141.77
mm.], superiorly, 67 lines [=141.77 mm.]; length of
centrum, laterally, 77 lines [=163 mm.], in the axis, 82
lines [=173.5 mm.]; breadth of anterior articular end,
77 lines [=163 mm.]; depth of anterior articular end,
74 lines [=156.6 mm.]; breadth of posterior articular end,
78 lines [=165 mm.]; depth of posterior articular end, 74
lines [=156.6 mm.]; breadth of neural arch, 42 lines
[=88.9 mm.]; and breadth of transverse process, 48 lines
[=101.5 mm].
Leidy’s description (1869, p. 442) of this vertebra is as
follows:
“The caudal vertebra, from the anterior part of the series, is
slightly longer than the breadth, and its articular extremities are
near circular and convex. The posterior abutments of the chevrons
extend nearly half the length of the body. The transverse processes
projected from near the middle of the latter about an inch and
three-fourths back of the edge of the anterior articulation. The
spinal canal is narrow, not more than seven lines in width.”
This very enticing theory, however, seems to be altogether
erroneous. In all the mandibles examined the dental canal
extends through the middle of the mandibular ramus as in
other mammals, but gives off a complex series of branches
to the dorsal portion of the ramus on both sides, the
branches running obliquely forward and upward, and
those of the inner side being generally much smaller than
the outer ones. This arrangement may be likened to a
trailing plant whose main stem or root (viz: Cynodon,
Bermuda grass) runs horizontally a little below the surface
of the ground, and sends out branches which extend up-
ward and forward, and penetrate the surface at intervals.
When studying broken fragments of mandibles one might
readily be deceived into believing that the two superim-
posed passages or aqueducts which are visible at the end
of a fragment are the openings of two separate canals
(dorsal and ventral) running in a parallel line inside the
mandible. In reality, however, the dorsal one is the broken
end of a branch which united with the true dental canal
at a point farther back. Looking carefully into such a
fragment when the foramina are all free of matrix, one can
see the various smaller branches extending out from the
dental canal on both sides, and when a fragment of a
mandible is broken off vertically their upward course can
be traced with certainty. Examination of the broken ends
of ten mandibles from the Calvert formation of comparable
dimensions, as well as three that are split lengthwise con-
firms this explanation. It is true that in Recent right
whales (Balaenidae) generally a groove or channel more
128
or less deep will be observed on the dorsal surface of the
mandible, but this is not to be confounded with the dental
(mandibular) canal which is situated lengthwise as usual
within the mandible.
Winge (1909, pp. 25-26) voiced his dissent from Cope’s
interpretation of the canals, but he seems inclined to accept
the statement that the dental canal may be divided into
an upper and lower passageway or aqueduct by a bony
partition. He calls attention to the fact that Brandt’s illus-
tration (1873, pl. 1, fig. 9) of the type mandible of Ceto-
therium rathkii exhibits what appears to be this peculiarity,
and remarks that the establishment of the new genus
Stphonocetus was, therefore, unnecessary. If this division of
the dental canal actually occurs, which seems improbable,
this would not suffice to distinguish Szphonocetus from
Cetotherium, and unless other characters can be found the
genus has no validity. The mandibles that have been
assigned by Cope to Stphonocetus, S. pusillus, S. expansus, and
S. priscus, do not differ from one another in other acceptable
diagnostic structural details. Hence the validity of the
smaller species assigned to Siphonocetus by Cope, which
were thought to be distinguishable among themselves on
the basis of mandibular fragments chiefly by the number
and arrangement of the gingival foramina on the inside
of the upper margin of the mandibular ramus, has not as
yet been confirmed by the acquisition of more complete
mandibles. Although no detailed studies of the extent of
individual variation in this respect have been made, it is
questionable how far this character is reliable as a criterion
of species. At present, however, about the only means of
distinguishing the mandibles is size, since the greater or
less convexity of the sides, though it may be of importance,
is very difficult to appraise, as it varies considerably along
the ramus from the anterior to the posterior end. The
internal gingival foramina are in a single row and quite
close to the dorsal margin of the mandible, and the external
mental foramina rather more distant from that margin.
TRETULIAS Cope
Tretulias Cope, 1895a, Proc. American Philos. Soc., Philadelphia,
vol. 34, no. 147, p. 143.
Type Species: Tretulias buccatus Cope.
Diagnosis: This genus was characterized by Cope as
follows: “Dental canal obliterated, and dental groove
without osseous roof. Gingival canals and foramina present
at one side of the alveolar groove.” Tretulias, like Ulias,
was considered by Cope (1895a, p. 139) to have the dental
(alveolar) groove fused with the dental (mandibular)
canal, though the former retained the gingival passages
and foramina.
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 5
TRETULIAS BUCCATUS Cope
Tretulias buccatus Cope, 1895a, Proc. American Philos. Soc.,
Philadelphia, vol. 34, no. 147, p. 143.
Type Specimen: Cope based this genus and species on
two fragments of mandibles, one “‘in fairly good preserva-
tion,”’ and the other shorter and considerably worn. The
last mentioned shorter specimen has not since been located.
The longer specimen is part of a strongly weathered left
mandible, length, 595 mm.; mandibular canal exposed on
its entire length by erosion or disintegration of dorsal
border of ramus; nine recognizable unusually broad (2-4
mm.) exposed gingival canals originating from mandibular
canal and located on dorsointernal border of outwardly
bowed ramus are directed forward. No. 9345, Division of
Vertebrate Paleontology, United States National Museum
(deposited by Maryland Geological Survey). Collector not
known.
Type Locality: No definite locality recorded.
Diagnosis: According to Cope’s interpretation, the mandib-
ular canal has been obliterated and an open alveolar or
gingivodental groove was not covered by a bony roof.
Gingival foramina and their anteriorly directed horizontal
grooves are present on the internal border of the ramus
along the alveolar groove. Cope thought it possible that
either the roof of the gingival groove failed to develop
external to the gingival foramina or the roof was developed
only above the gingival foramina, leaving the remainder
of the gingival groove open. The external series of canals
mentioned by Cope are not now recognizable on the type
mandible.
Winge (1909, p. 27; True, 1912, pp. 6-7) has observed
that Cope’s interpretation cannot be correct and that his
alveolar groove is unquestionably the mandibular canal.
Breakage or erosion of the dorsal border of this type man-
dibular fragment has exposed the mandibular canal on
its entire length. This canal is at least 23 mm. wide near
the posterior broken off end and not more than 7 mm. at
the anterior end of this fragment. The narrowing of this
canal anteriorly and its greater width posteriorly indicate
that this type fragment represents a section immediately
anterior to the middle of the length of the complete man-
dible. Preservation of the gingival foramina and grooves
may be attributed to uneven wear of the dorsal border of
the ramus and this erosion was less effective in reducing
the internal than the external wall of the mandibular
canal. A longitudinal fissure or crack developed above the
ventrointernal margin of this mandible was regarded as the
Meckelian fissure by Cope and as an artificial crack by
Winge (1909, pp. 28-29; True, 1912, pp. 7-8).
The ventral surface of this type mandibular fragment has
also been eroded and, consequently, the vertical diameter
of the ramus in this region when complete is uncertain.
MIOCENE CALVERT MYSTICETES
The maximum transverse diameter at the posterior end is
75 mm. and 43 mm. near the anterior end. It seems ob-
vious, however, that this section was part of a more robust
or physically mature mandible than the type of Ulias
moratus. The general conditions responsible for the
weathered condition of this type specimen seem to have
been similar to those for U. moratus. Whatever deterioration
ensued during subsequent storage in the collections of the
Maryland Geological Survey at The Johns Hopkins
University, Baltimore, Maryland, was certainly of a minor
nature. Both Winge and True regarded the validity of
Cope’s generic diagnosis as doubtful.
The type of Tretulias buccatus is a portion of a left man-
dible anterior to the middle of its length which is not dis-
tinguishable either in dimensions or in conformation from
mandibles of comparable size of at least two Calvert ceto-
theres. Since this eroded type specimen lacks recognizable
differential features, it is not identifiable and should be
eliminated from the Calvert faunal list.
ULIAS Cope
Ulias Cope, 1895a, Proc. American Philos. Soc., Philadelphia,
vol. 34, no. 147, p. 141.
Type Species: Ulias moratus Cope.
Diagnosis: This genus was characterized by Cope as
follows: “Mandible with the gingivodental canal open
throughout most if its length, closed only near its apex.
Gingival foramina represented by a few orifices on the
alveolar border near the distal extremity.”
The mandible of Ulias was thus considered by Cope
(1895a, p. 139) to represent a further degeneration from
the condition attributed to Siphonocetus whereby the dental
(alveolar) groove and the dental (mandibular) canal
became united although the dental groove remained open.
As a result of erosion, the few supposedly “‘gingival”’
foramina on the dorsal border near the distal end were
misinterpreted inasmuch as they are unquestionably
grooves or channels leading to external mental foramina
in locations corresponding to those on the mandibles of
USNM 23494.
ULIAS MORATUS Cope
Ulias moratus Cope, 1895a, Proc. American Philos. Soc., Phila-
delphia, vol. 34, no. 147, p. 141.
Type Specimen: USNM 10595. Right mandible, length
along external curvature, 1645 mm.; dorsal border of the
ramus is broken or worn off, exposing for a considerable
portion of its length the wide open bottom of the mandib-
ular canal; a section 230 mm. in length anterior to the
level of the coronoid process is filled in by a hard cemented
sandy marl matrix. Apparently the piece from the distal
third of this ramus which was mislaid when Cope estab-
129
lished the species, was subsequently located and attached
correctly to the adjacent portions of the mandible. The
measurements of the type mandible published by Cope
(1895a, p. 143) should be disregarded. The type mandible
has been illustrated by Case (1904, pl. 24, fig. la, 1b).
Deposited by the Maryland Geological Survey in Division
of Vertebrate Paleontology, United States National Mu-
seum; Collector not known.
Type Locality: No definite locality recorded.
Diagnosis: Cope (1895a, pp. 141-142) believed that this
genus at maturity retained characters which are present
in fetal right whales (Balaenidae) and asserted that the
type mandible was characterized by these features: Gingi-
vodental canal open throughout most of its length, closed
near apex. Gingival foramina represented by a few orifices
on the alveolar border near the distal extremity. Alveolar
groove is continuous with the dental canal, and is per-
manently open. Long series of mental foramina character-
istic of the true whales absent; terminal mental foramen
at distal end of ramus retained.
True (1912, p. 5) correctly stated that no internal gingival
canals were visible. At least three of the anteriormost
external mental foramina and the grooves leading forward
therefrom were not completely obliterated by erosion.
Examination of the type mandible alongside other Calvert
cetothere mandibles clearly demonstrates that most of the
mental foramina and their anteriorly directed external
grooves, as well as the internal nutrient or gingival fora-
mina, when the mandible was complete, were located on
the missing dorsal border above the level of the preserved
ventral portion.
Winge (1909, pp. 26-27; True, 1912, p. 6) commented
that “Cope’s interpretation is certainly not correct,” and
correctly concluded that the asserted lack of mental fora-
mina raised reasonable doubts as regards the undamaged
condition of the type mandible.
This weathered type mandible (Case, 1904, pl. 24, figs.
la, 1b) presumably was submerged under water for some
time; it agrees in general preservation with other portions
of cetothere mandibles recovered from exposures along
the lower portion of the Patuxent River, which have the
mandibular canal filled with an indurated sandy matrix.
Neither Winge nor True were afforded an opportunity
to actually handle this type mandible which, at the time
their articles were published, apparently, was not readily
accessible in the stored collections of the Maryland Geo-
logical Survey at The Johns Hopkins University, Baltimore,
Maryland.
Additional measurements (in mm.) are as follows: Trans-
verse diameter of ramus 100 mm. behind anterior end, 38;
300 mm. behind, 48; 400 mm. behind, 53; 700 mm.
behind, 55; 900 mm. behind, 56; and 1200 mm. behind, 57.
130 UNITED STATES NATIONAL MUSEUM BULLETIN 247
Cope (1896, p. 141) suggested that the mandible on
which the genus Ulias was founded might belong to either
the genus Metopocetus or Cephalotropis, although there was
no direct evidence to support this assumption. The length
(1645 mm.) of the type mandible of Ulias moratus is almost
the same as that of Mesocetus pinguis (1642 mm.). If Cope’s
view of the internal structure of the mandible of Ulias
should be proven correct, which does not seem likely, no
comparisons would be necessary, as this type mandible was
supposed to have a deep dorsal conjoined dental (mandi-
bular) canal and alveolar groove, entirely open above,
while the mandible of Mesocetus is roofed over above the
mandibular canal as in other cetotheres. Cope’s interpre-
tation of the Ulias mandible is unquestionably erroneous,
as already mentioned, but at present the allocation of this
type mandible to any contemporary species involves a
certain amount of uncertainty. If roofed over, as it was
undoubtedly in life, its vertical diameter at the distal end
would be approximately the same as the mandible of
Mesocetus longirostris (90 mm.), but much less than the same
measurement of the type mandible of M. pinguis (123 mm.) ;
otherwise, it is not feasible to make any precise comparisons.
It seems certain, nevertheless, that Ulias represents some
PART 5
form of cetothere rather than a right whale allied to
Balaena, in view of the transversely flattened anterior
extremity and the presence there of a lower internal ledge.
The shape of the entrance to the mandibular canal and the
convexity of the outer wall of the mandible in this region
are not materially different from mandibles of other
Calvert mysticetes.
Both Winge and True regarded the validity of Cope’s
generic diagnosis as doubtful. The missing dorsal border
above the mandibular canal on the entire length of the
ramus most certainly contributed to this misleading generic
diagnosis. The loss of the coronoid process and more
especially the articular surface of the condyle and the
ventral angle, in addition to the destroyed dorsal border
of the ramus, render direct comparisons with other man-
dibles of comparable size useless. Nevertheless, in length
and general form the type right mandible of Ulias moratus
does not appear to have exhibited, when complete, appreci-
able differences from a Calvert formation right mandible
(USNM 16760; length, 1650 mm.). This fossil mysticete
mandible is not identifiable and hence Ulias moratus should
be removed from the Calvert faunal list.
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BRANDT, JOHANN FRIEDRICH
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Case, ERMINE COWLES
1904. Mammalia. Jn W. B. Clark, Systematic paleontology of the Miocene deposits of
Maryland. Maryland Geol. Surv., Miocene, pp. 1-56, atlas, pls. 10-26.
Core, EDwArD DRINKER
1868a. [Description of Eschrichtius cephalus, Rhabdosteus latiradix, Squalodon atlanticus and S. mento].
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1890) August 8, 1890.
The Cetacea. American Nat., vol. 24, no. 283, pp. 599-616, figs. 8, pls. 20-23 (July 30,
1895a. Fourth [=Fifth] contribution to the marine fauna of the Miocene period of the United
States. Proc. American Philos. Soc., Philadelphia, vol. 34, no. 147, pp. 135-155,
pl. 6 (April 5, 1895). May 29, 1895.
MIOCENE CALVERT MYSTICETES 131
1895b. The phylogeny of the whalebone whales. American Nat., vol. 29, no. 342, pp. 572-
573. June 1895.
1896. Sixth contribution to the knowledge of the Miocene fauna of North America. Proc.
American Philos. Soc., Philadelphia, vol. 35, no. 151, pp. 139-146, pls. 11-12 (May
15, 1896). August 13, 1896.
Doran, ALBAN HENRY GRIFFITHS
1878. Morphology of the mammalian ossicula auditus. Trans. Linnean Soc. London, ser.
2 (Zool.), vol. 1, pt. 7, pp. 371-497, pls. 58-64.
Gervais, Francois Louts PauL
1848-1852. Zoologie et Paléontologie Francaises (Animaux Vertébrés) ou Nouvelles Recher-
ches sur les Animaux Vivants et Fossiles de la France, Paris. Vol. 1: Contenant
Lénumération méthodique et descriptive des espéces ainsi que les principes de leur
distribution géographique et paléontologique, pp. viii+1-271, 1848; vol. 2: Con-
tenant l’explication des planches et divers mémoires relatifs aux animaux vertébrés,
pp. 142 (partly unnumbered for pls. 1-80), 1849; vol. 3, atlas, 80 pls.
Gray, JOHN EDWARD
1864. Notes on the whalebone whales; with a synopsis of the species. Ann. and Mag. Nat
Hist., London, ser. 3, vol. 14, no. 83, pp. 345-353. November 1864.
1866. Catalogue of seals and whales of the British Museum. Publ. Brit. Mus. (Nat. Hist.),
London, ed. 2, pp. vii+-402, figs. 101.
Hay, OLtver PERRY
1902. Bibliography and catalogue of the fossil Vertebrata of North America. Bull. no. 179
U.S. Geol. Surv., Dept. Interior, 868 pp.
Heim, Oscar LEsiiz
1939. Preliminary report on fossil whale mandibles. Bull. Nat. Hist. Soc. Maryland, vol. 9,
no. 12, pp. 107-110, 3 figs. August 1939.
Kapic, OTTOKAR
1907. Mesocetus hungaricus Kadic, eine neue Balaenopteridenart aus dem Miozdn von
Borbolya in Ungarn. Mitteil. Jahrbuche Kgl. Ungarischen Anstalt, Budapest,
vol. 16, no. 2, pp. 21-91, 70 figs., 3 pls.
KeLitocce, REMINGTON
1924. Description of a new genus and species of whalebone whale from the Calvert Cliffs,
Maryland. Proc. U.S. Nat. Mus., vol. 63, pp. 1-14, pls. 6. February 5, 1924.
1925. Additions to the Tertiary history of the pelagic mammals on the Pacific coast of North
America. Contr. Palaeont., Carnegie Inst. Washington, publ. 348, 120 pp., 49 figs.,
13 pls. April 1925.
1940. On the cetotheres figured by Vandelli. Bol. Mus. Mineral. Geol. Univ. Lisboa, pp.
1-12, 3 pls.
1965. Fossil marine mammals from the Miocene Calvert formation of Maryland and Virginia,
1: A new whalebone whale from the Miocene Calvert formation. U.S. Nat. Mus.
Bull. 247, pt. 1, pp. 1-45, figs. 1-28, pls. 1-21. October 15, 1965.
Lewy, JosEPH
1852. [Descriptions of two fossil species of Balaena, B. palaeatlantica and B. prisca.] Proc. Acad.
Nat. Sci. Philadelphia, vol. 5, no. 12, pp. 308-309.
1869. The extinct mammalian fauna of Dakota and Nebraska, including an account of some
allied forms from other localities, together with a synopsis of the mammalian remains
of North America. Journ. Acad. Nat. Sci. Philadelphia, ser. 2, vol. 7, pp. 1-472,
30 pls.
LILLJEBORG, WILHELM
1861. Hvalben funna i jordon pa Grasén i Roslageni Sverige. Féredrag vid Naturforska-
remétet i Képenhamm, 1860, pp. 599-616.
1866. Synopsis of the cetaceous Mammalia of Scandinavia (Sweden and Norway). Jn Recent
memoirs on the Cetacea by Professors Eschricht, Reinhardt and Lilljeborg. The Ray
Society, London, 1866, pp. 221-309, figs. 5.
275-699 683
132
UNITED STATES NATIONAL MUSEUM BULLETIN 247
Lit1rjEBorG, WILHELM—Continued
1867. On two subfossil whales discovered in Sweden. Nova Acta Soc. Sci., Upsala ser. 3,
vol. 6, pp. 1-48, pls. 1-11.
Osborn, Henry FAIRFIELD
1931. Cope: Master naturalist. The life and letters of Edward Drinker Cope with a bibli-
ography of his writings classified by subject. Princeton Univ. Press, pp. xv-+740,
30 figs.
TRUE, FREDERICK WILLIAM
1907. Remarks on the type of the fossil cetacean Agorophius pygmaeus (Miiller). Publ. 1964
Smithson. Inst., Washington, 8 pp., pl. 6.
1912. The genera of fossil whalebone whales allied to Balaenoptera. Smithsonian Misc.
Coll., vol. 59, no. 6, pp. 1-8. April 5, 1912.
TuRNER, WILLIAM
1871. On the so-called two-headed ribs in whales and in man. Journ. Anat. and Physiol.,
vol. 5, pp. 318-362.
VAN BENEDEN, PIERRE JOSEPH
1859. Ossements fossiles découverts 4 Saint Nicolas en 1859. Bull. Acad. roy. Sci. Belgique,
Bruxelles, vol. 8, no. 11, pp. 123-146.
1872. Les baleines fossiles d’Anvers. Bull. Acad. roy. Sci. Belgique, Bruxelles, ser. 2, vol. 34,
no. 7, pp. 6-20. July 1872.
1880. Les Mysticétes 4 courts fanons des sables des environs d’Anvers. Bull. Acad. roy. Sci.
Lettres et Beaux-Arts, Belgique, Bruxelles, ser. 2, vol. 50, no. 7, pp. 11-27.
1882. Description des ossements fossiles des environs d’Anvers, Part 3: Cétacés. Genres:
Megaptera, Balaenoptera, Burtinopsis and Erpetocetus. Ann. Mus. roy. d’Hist. nat.
Belgique, Bruxelles, ser. Paléontologique, vol. 7, pp. 90, pls. 40-199.
1884. Une baleine fossile de Croatie, appartenent au genre Mesocete. Mém. Acad. roy.
Sci. Belgique, ser. 2, vol. 45, no. 2, pp. 1-29, pls. 1-2.
1885. Description des ossements fossiles des environs d’Anvers, Part 4: Cétacés. Genre:
Plesiocetus. Ann. Mus. roy. d’Hist. nat. Belgique, Bruxelles, ser. Paléontologique,
vol. 9, pp. 40, pls. 30.
1886. Description des ossements fossiles des environs d’Anvers, Part 5: Cétacés. Genres:
Amphicetus, Heterocetus, Mesocetus, Idiocetus and Isocetus. Ann. Mus. roy. d’Hist. nat.
Belgique, Bruxelles, ser. Paléontologique, vol. 13, pp. 139, pls. 75.
VAN BENEDEN, PIERRE JOSEPH, and Gervais, PAUL
1874-1880. Ostéographie des Cétacés vivants et fossiles, Paris, text, pp. viii+634; atlas,
pls. 64.
Van DeinsE, ANTONIUs BouDEWIJN, and JuNGE, GEORGE CHRISTOFFEL ALEXANDER
1937. Recent and older finds of the California gray whale in the Atlantic. Temminckia,
Leiden, vol. 2, pp. 163-188, pls. 4-11.
WALMSLEY, ROBERT
1938. Some observations on the vascular system of a female fetal finback. Contr. Embryol.,
Carnegie Inst. Washington, Publ. 496, no. 164, pp. 107-178, 27 figs., 5 pls. May 31,
1938.
Wince, Apo_r HERLUF
1909. Om Plesiocetus og Sqvalodon fra danmark. Vidensk. Meddel. fra den naturhist.
Foren i Kjdbenhaven for 1909, pp. 1-38, pls. 1-2. April 20, 1909.
PART 6
6. A Hitherto Unrecognized Calvert Cetothere
OTWITHSTANDING THE PRESENCE of the odontocetes
Squalodon, Eurhinodelphis, and Schizodelphis (Cyrtodelphis)
in the Miocene marine faunas of both the Calvert of Mary-
land and Virginia and the Anversian sands of the Belgian
Antwerp basin, the possibility of the occurrence of identical
or related mysticetes in these deposits has not been given
serious consideration.
To arrive at a more precise evaluation of the generic
and specific differentiation of the Calvert cetotheres, skulls,
tympanic bullae, periotics, mandibles, vertebrae, and
limb bones were assembled for direct visual comparison.
The Calvert skeletal materials representing several distinct
types were compared with Van Beneden’s large scale
illustrations, supplemented by my own descriptive notes
and measurements of the Belgian types.
Since the bones of Recent species serve as a guide for the
establishment of genera and species when available for
comparison, Van Beneden (1880, pp. 11-13) concluded,
as a result of his review of the skeletons of fossil and living
mysticetes in the collections of the Brussels museum, to
base his descriptive characterizations of the genera of the
Antwerp basin mysticetes on the articular condyle of the
mandible and the modifications of the entrance to the
mandibular canal. The reliability of the mandibular
condyle as an invariable generic character will be reviewed
later under the mandible of Parietobalaena palmeri. Differenti-
ations of species were based on the periotic and its processes.
He also observed that the importance of the tympanic
bulla (Van Beneden, 1836) had been exaggerated by
naturalists. In this introductory comment also, Van Bene-
den decided to suppress the generic name Cetotherium
inasmuch as the condyle of the mandible was unknown and
no distinctive generic characters were designated by Brandt
(1843a-c, pp. 20, 241, 270).
Relatively little if any consideration was given by Van
Beneden to skeletal modifications that are attributed now
either to growth or variability. Skulls, mandibles, and other
skeletal elements of physically immature individuals were
more numerous than those of adults and in many instances
comprised the sole representation of a particular form in the
Belgian collections. This condition also is thought to have
prevailed in the Calvert geologic area. Physically immature
and juvenile cetothere skeletal remains are encountered
far more frequently than the fully adult in the Calvert
deposits along the western shore of Chesapeake Bay.
These occurrences tend to support the belief that these
waters were sought during the calving and nursing season
by Miocene mysticetes.
Abel (1938, pp. 4-5) following his review of the Antwerp
basin collections concluded that the osteological basis for
described fossil mysticetes was very unsatisfactory, but
recognized as valid five upper Miocene (Anversian) species
allocated to the genera Jsocetus, Mesocetus, and Herpetocetus.
Mysticetes related to Isocetus and Mesocetus are now recog-
nized in the Calvert fauna.
This Calvert study also lead to a review of the applica-
bility of several generic names to Miocene mysticetes.
The reference by Van Beneden of mysticete skeletal re-
mains excavated in the Antwerp basin to the genera
Idiocetus and Heterocetus is here regarded as questionable.
Some uncertainty will probably always persist regarding
the association of skeletal elements recovered from the
Antwerp marine deposits. Van Beneden (1886, p. 34) in
commenting on the Italian fossil cetaceans, remarks that
the bones there are associated in such a manner that they
clearly represent the same individual, while at Antwerp
the skeletons are dispersed and the bones intermingled.
The genus Jdzocetus (genotype, J. guicciardiniz) was proposed
by Capellini (1876, pp. 12-13; 1905, pp. 71-80, pls. 1, 2)
for a tympanic bulla and attached periotic, portions of
the skull, right mandible (length, 1650 mm.), atlas, and
scapula from the lower Pliocene (Plaisancian) “argilla
turchina” at Montopoli del Valdarno inferiore, Tuscany,
Italy.
133
134
The Italian lower Pliocene Jdiocetus is a balaenopterine
whale whose tympanic bulla and periotic are readily
distinguishable from the upper Miocene species referred
to this genus by Van Beneden.
Capellini (1877, p. 613, pl. 1, figs. 15) based the genus
Heterocetus (genotype, H. guiscardii) on a left mandible
(length, 1305+ mm.), a left tympanic bulla, a posterior
process of a periotic, and four cervical vertebrae from the
upper Miocene (Messiniano) conglomerate at Briatico,
Golfo di Eufemia, Calabria, Italy. The tympanic bulla
(length, 90 mm.) of the upper Miocene Italian Heterocetus
is larger than that of the lower Pliocene (Diestian) Belgian
Heterocetus affinis (length,70 mm.), according toVan Beneden
(1886, p. 26).
Abel (1938) neither lists nor discusses the species referred
to the genera, Jdiocetus and Heterocetus, by Van Beneden.
Considering the uniformity of the functions of the inner
ear, it may be anticipated that its structural components
will be less susceptible to modification attributed to acci-
dental alterations in cranial architecture than those ob-
servable in the protective outer structures that serve for
attachment of the periotic and the tympanic bulla. Perhaps
the greatest importance, however, should be attached to
differences observable in those anatomical structures that
appear to subserve identical functions. One of the most
obvious modifications of the cetothere periotic is observable
in the openings of the aqueducts and the internal acoustic
meatus on the cerebral face of the balaenopterine periotic.
It is still doubtful that the modifications of the anterior and
posterior processes of the periotic bear an obvious and
direct relation to some functional requirement, which itself
is dependent on some particular circumstance of the
environment.
DIOROCETUS, new genus!
Type Species: Diorocetus hiatus, new species.
Diagnosis: Rostrum strongly tapered anteriorly; an in-
cisure of variable length, commencing near the posterior
end of each maxillary internal to the base of its postero-
external process, extends obliquely forward toward the
maxillary-premaxillary contact along the mesorostral trough
and separates the triangular area behind it into a dorsal
and yentral plate; backward thrust of rostrum limited,
median rostral elements (ascending processes of maxillaries,
premaxillaries, and the nasals) not carried backward beyond
the level of the posteroexternal processes of the maxillaries
that project laterally beyond the preorbital angles of the
supraorbital processes on the immature type skull, but to
1 In allusion to the elongated incisure that divides the posterior end
of each maxillary into a dorsal and ventral plate.
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 6
level of center of orbit on more mature referred skull; no
transverse temporal crest developed on supraorbital process;
elongated nasals located for most part anterior to level of
preorbital angle of supraorbital processes; apex of supra-
occipital shield thrust forward to or slightly beyond level
of anterior ends of zygomatic processes; palatines elongated;
lateral descending processes of basioccipital knob-like,
smaller than pterygoid fossa; anterior process of periotic
compressed transversely; a deep lengthwise groove for facial
nerve on ventral surface of posterior process; groove behind
stapedial fossa on posterior face of pars labyrinthica extends
from posterointernal angle of posterior process to cerebral
face of pars cochlearis; horizontal ramus of mandible robust,
its depth anteriorly about one fifteenth of its length;
coronoid process small and low; condyle expanded from
side to side, with deep groove above angle on internal
surface for attachment of internal pterygoid muscle; cervi-
cal vertebrae separate; scapula fan shaped, with well-
developed acromion and coracoid process, prescapular fossa
narrow and its height about two thirds of its anteroposterior
diameter.
DIOROCETUS HIATUS, new species
Type Specimen: USNM 16783. Skull essentially com-
plete except for left half of cranium; both lachrymals and
jugals also missing; right periotic attached but no right
tympanic bulla; right and left mandibles lack condyles
and adjacent portion of ramus behind coronoid process;
axis, sixth and seventh cervical and first dorsal vertebrae;
whole or portions of seven epiphyses; one chevron; and
four ribs. Collectors, William F. Foshag and Remington
Kellogg; July 6-15, 1941.
Horizon and Locality: In zone 14 (12 inches above
base), 18 feet above beach level in third cliff, 2500 feet
south of mouth of Parker Creek, Calvert County, Maryland.
Calvert formation, middle Miocene.
Referred Specimens: Three as follows: (1) USNM
16871: incomplete rostrum; coll. Alton C. Murray, Oct.
23, 1942; face of cliff 1570 yards north of road end at
Governor Run, Calvert Co., Md., Calvert formation,
middle Miocene. (2) USNM 23494: skull partially dis-
articulated when excavated, but since restored; supra-
orbital processes of frontals detached but restored; rostrum
essentially complete except for damaged portions of maxil-
laries; nasals, lachrymals, and jugals missing. Right and
left tympanic bullae; right and left periotics; right and
left mandibles; 1 cervical, 5 dorsal, 11 lumbar, and 5
caudal vertebrae; 3 chevrons; right and left scapula; head
of right humerus; right and left ulna; 7 carpals; 5 meta-
carpals; 2 phalanges; and 7 ribs; coll. Albert C. Myrick,
Jr., August 1962; about 300 yards north of road end at
Governor Run, in sandy clay near base of zone 14, 2 feet
UNRECOGNIZED CALVERT CETOTHERE 135
Ficurre 53.—Dorsal view of skull, USNM 16783, of Diorocetus
hiatus, with left side of cranium restored. Abbrs.: ant.n.,
antorbital notch; Bo., basioccipital; c., occipital condyle;
Ex.oc., exoccipital; f.m., foramen magnum; f.max., maxillary
foramen or incisure; f.ov., foramen ovale; Fr., frontal; h.pt.,
above clay ledge between two shell layers, Calvert Co.,
Md., Calvert formation, middle Miocene. (3) USNM
16567: 11 caudal vertebrae; 3 detached epiphyses; 1
chevron; collectors, William F. Foshag and Remington
Kellogg, Aug. 5, 1940; 965 yards south of mouth of Parker
Creek, partially in sandy marl and yellowish sand of zone
14, about 14 feet above beach level, Calvert Co., Md.,
Calvert formation, middle Miocene.
Skull
Except for the left side of the braincase (USNM 16783;
pl. 49), which had been broken off and lost when a section
of the exposed cliff face fell on the tide-washed narrow strip
of the shore below, this skull was exceptionally well
preserved.
The type skull (fig. 53) is readily characterized by the
wide incisure (length, 145 mm.), which, commencing 30
mm. distant from the external edge of the maxillary in
front of the antorbital notch, extends obliquely forward
toward the mazxillary-premaxillary contact along the
mesorostral trough. This incisure separates the triangular
portion of the maxillary behind it into a dorsal and a
ventral plate and forms the walls of a broad cavity that
extends backward ventrally to the anteroventral edge of
the supraorbital process of the frontal. A similar modifica-
tion of the posterior rostral portions of the mazxillaries
exists on two additional specimens (USNM 16871, 23494).
On the largest skull (USNM 23494) this incisure (fig. 54)
is not continuous but is divided in the right maxillary by
intervening bone into three dorsal openings, the internal
one large (length, 44 mm.) and two smaller openings
(lengths, 22 and 32 mm.) in an overall interval of 147 mm.
Three large foramina are also present in this maxillary,
one anterior to the incisure, and two behind it. In the left
maxillary, this incisure is divided into one large opening
(length, 63 mm.) and one small (length, 28 mm.) in an
interval of 137 mm.; it terminates 41 mm. inside the outer
edge of this bone. Three small foramina are located behind
the incisure.
In the left maxillary of the detached rostrum (USNM
16871), one very large incisure (length, 142 mm.; depth
65 mm.) terminates externally about 47 mm. from the
outer edge of this bone. Behind this incisure there are three
hamular process of pterygoid; j.n., jugular notch or incisure;
l.pr., lateral or descending protuberance of basioccipital; Max.,
maxilla; m.e.a., channel for external auditory meatus; Na.,
nasal; 0.c., optic canal: Pa., parietal; Pal., palatine; pgl. post-
glenoid process; Pmx., premaxilla; pr.a., anterior process of
periotic; pr.p., posterior process of periotic; Pt., pterygoid;
pt-f., pterygoid fossa; S.oc., supraoccipital; Sq., squamosal;
s.or.pr., supraorbital process of frontal; Ty., tympanic bulla;
Vo., vomer; zyg., Zygomatic process.
136
small foramina, and one in front of it. Most of the right
incisure was destroyed when the posterior end of this
maxillary broke off; this incisure terminates 52 mm. inside
of the outer edge of this bone. Four smaller foramina are
located anterior to the incisure.
No other fossil mysticete having a similarly modified
maxillary seems to have been recorded in the literature.
A lithographic plate (True, 1907, pl. 6) prepared in 1850
under the supervision of Louis Agassiz for the type skull of
Agorophius pygmaeus, however, shows a relatively large
circular foramen in each maxillary in a position com-
parable to this maxillary incisure.
Dissection of a fetal female finback (Balaenoptera physalus)
by Walmsley (1938, p. 142-143, fig. 14) has shown that
the main maxillary artery after passing forward along the
pterygoid divides into a leash of small branches that pass
ventrally into the maxillary bone to supply the baleen
plates. Branches of a superficial temporal branch of this
maxillary artery pass forward to the top of the snout where
they divide further into a “‘leash of exceedingly fine twigs.”
This portion of the rostrum is drained by the maxillary
vein. Skulls of Recent as well as fossil mysticetes, whose
rostra are sufficiently complete to permit detailed com-
parisons, have the maxillaries pierced dorsally by one or
more relatively small foramina for the passage of vascular
vessels and nerves, but at more anterior and inward
positions.
In the absence of even a sketchy geological record of the
sequence of prior adaptive alterations, the infraorbital
foramen of the carnivore skull may also furnish a clew as to
the functional purpose of this elongate maxillary incisure.
Some of the carnivores, at least, have infraorbital nerves,
which are terminal branches of the maxillary nerve (Trige-
minus IJ) that accompany the infraorbital branches of
the internal maxillary artery through the infraorbital
foramen and then both divide into several smaller branches
to supply the snout. On this fossil cetothere skull ramifica-
tion of these nerves and arterial branches may have been
associated also with more numerous and more closely
spaced tactile facial vibrissae on the snout.
The skull is also characterized in part by the pronounced
tapering of the rostrum, limited interdigitation by the
backward overriding of median rostral elements on the
frontals, a moderate forward thrust of supraoccipital, and
the parietals; exposure of frontals in median interorbital
region not markedly reduced; intertemporal region broad,
not pinched in; temporal fossa wide; slender zygomatic
processes; and normal postglenoid processes.
DorsaL view.—From a dorsal view (fig. 53) the apex of
the subtriangular supraoccipital shield projects forward to
or slightly beyond the level of the anterior ends of the
zygomatic processes. The forward overthrust has carried
the anterior ends of the parietals to the level of the center
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 6
2,
pel.
EXx.06.
Ficure 54.—Dorsal view of skull, USNM 23494, of Diorocetus
hiatus. For abbreviations, see figure 53.
UNRECOGNIZED CALVERT CETOTHERE 137
of the orbit. The zygomatic processes are directed obliquely
outward and the nasal bones are elongated. No transverse
temporal crest was developed on the supraorbital process
of the frontal.
Anterior to the antorbital notch, the lateral edge of each
maxillary on the anteriorly attenuated rostrum is essentially
straight. The rostrum constituted 60 to 75 percent of the
total length of the skull. The maxillaries are abruptly
widened at the base by protuberant posteroexternal
processes that project laterally beyond the preorbital
angles of the supraorbital processes of the frontals. The
concave dorsal surface of each of these posteroexternal
processes of the maxillaries presumably lodged the lachrymal
bone, which was not preserved. The jugal, likewise, was
not associated with this skull. Each maxillary is very thin
along its lateral borders, and the dorsal surface of each
slopes gradually from the maxillary-premaxillary sutural
contact to its outer edge. The dorsal ascending process of
each maxillary is short and wide (100 mm.) and extends
backward to the level of the posterior ends of the nasals.
Except for the internal broad ascending process, each
maxillary does not override the supraorbital process of the
frontal, but is separated from it by a gap. This condition
may possibly be attributed to physical immaturity. Three
additional nutrient foramina as well as two or more small
foramina are located near the internal border of each
maxillary.
In front of the anterior end of the vomer, which extends
forward to within 535 mm. of the anterior extremity of
the right premaxillary, the opposite maxillaries do not
meet on the midline to form the bottom of the mesorostral
trough. Each premaxillary on this anterior portion of the
rostrum is curved downward internally, contributing the
dorsal portion of the lateral wall of the mesorostral trough
of the rostrum. Each premaxillary attains its maximum
width (65 mm.) 55 mm. behind the anterior end of the
maxillary and projects forward about 50 mm. beyond the
anterior end of the corresponding maxillary. The slender
facial or ascending process of each premaxillary is lodged
in a narrow groove on the dorsointernal border of the
corresponding maxillary and is also in sutural contact
with grooves on the frontal; it terminates near the posterior
end of the adjacent nasal bone. The dorsal surface of each
premaxillary is flattened in the region of the nasals, where
it is also relatively thin. In front of the nasal bones each
premaxillary follows the curvature of the widened narial
fossa in the mesorostral trough and, also, progressively
increases in depth as well as in width, the dorsal surface
becoming more noticeably convex except for the flattening
tendency near the anterior end.
The backward thrust of the median portion of the ros-
trum on the larger skull (USNM 23494; pl. 50) has carried
the ends of the ascending processes of the maxillaries and
premaxillaries to the level of the center of the orbit. Conse-
quently, the interlocking of the rostral and cranial elements
has been accomplished mainly by the thin plate-like ventral
border of the maxillary, the vomer, the palatines, and the
pterygoids.
The dorsal narial fossa in the mesorostral trough occupies
an interval of at least 350 mm. anterior to the extremities of
the nasal bones; it attains a maximum width of 100 mm.,
about 180 mm. in front of the nasals. Although the meso-
rostral trough is not completely roofed over for a distance
of 800 mm., the opposite premaxillaries anterior to the
narial fossa gradually close over this gap.
The long slender nasal bones are wedged in between the
ascending processes of the opposite premaxillaries; their
posterior ends are mortised into the frontals and anteriorly
they overhang the hinder portion of the narial fossa; the
anterior ends of these nasal bones are widened; they extend
backward to the level of the posteroexternal processes of
the maxillaries that project laterally beyond the preorbital
angles of the supraorbital processes on the immature type
skull and to level of center of orbit on more mature referred
skull.
The frontal bones are exposed for an interval of not more
than 40 mm. on the midline of the interorbital region
between the posterior ends of the overriding rostral bones
and the intertemporal region contributed by the parietals.
Each frontal slopes gradually downward from the dorsal
surface of the interorbital region to the orbital rim of its
supraorbital process. No transverse crest is developed on
either supraorbital process. The preorbital angle of the
supraorbital process of the frontal is rounded and _pre-
sumably is separated from the lateral extension of the
posteroexternal end of the maxillary by the interposition
of the lachrymal bone. The slender postorbital projection
is extended backward to meet the anterior end of the
zygomatic process. The orbital rim of the supraorbital
process is quite thin except at the thickened anterior and
posterior angles.
The opposite parietals, which meet medially to constitute
the intertemporal ridge, are overlapped above and behind
by the outer borders of the upper portion of the triangular
supraoccipital shield. The thin anterior border (30-+ mm.)
of the parietal is groved ventrally and overlaps the antero-
posteriorly directed ridges on the median portion of the
interorbital region of the frontal. The vertical diameter of
each parietal is equivalent to about two-thirds of its antero-
posterior diameter and comprises a major portion of the
lateral wall of the braincase. Below the level of the supra-
orbital process of the frontal, the lower edge of the parietal,
on another skull (USNM 23494), is in contact with the
dorsal edge of the alisphenoid, behind which the sutural
contact between the parietal and the squamosal extends
138
backward ventrally and then upward to meet the lateral
crest contributed in part by the supraoccipital shield.
The squamosal contributes the posterolateral portion of
the braincase. Commencing anteriorly at its contact with
the pterygoid, the squamosal curves backward, outward,
and forward to the extremity of its zygomatic process to
constitute the hinder limit of the temporal fossa. A shallow
trough on the dorsal surface of the squamosal extends
backward from about the level of the anterior face of the
postglenoid process to the lambdoid crest. The zygomatic
process is slender and is directed obliquely outward and
forward. The lambdoidal crest is continued forward on
the dorsal surface of the zygomatic process.
Except at their extremities the exoccipitals are almost
hidden from a dorsal view by the lambdoid crest. The
Ficure 55.—Posterior view of skull, USNM 16783, of Diorocetus
hiatus. For abbreviations, see figure 53.
transverse diameter (330 mm.) of the triangular occipital
shield of the larger skull (USNM 23494) at the level of the
foramen magnum exceeds the greatest distance (230 mm.)
from the dorsal rim of the foramen magnum to the apex.
The forward thrust of the hinder elements of the skull has
pushed the apex of the supraoccipital shield to the level of
the anterior end of the zygomatic process. The lower
portion of the triangular supraoccipital shield is depressed
noticeably below the level of its lateral crestlike margins.
From a dorsal view the occipital condyles appear relatively
small and not protuberant.
PosTERIOR viEW.— The subtriangular occipital shield is
constituted by the dorsally attenuated supraoccipital and
the relatively small lateral exoccipitals. Ventrally each
lambdoid crest (fig. 56) does not quite follow the posterior
limit of the corresponding squamosal and turning abruptly
upward at about the level of the center of the foramen
magnum continues along the external margin of the supra-
occipital to its pointed apex.
The relatively small exoccipital bones, which are not
noticeably thickened anteroposteriorly, constitute the lateral
wings of the occipital shield and are directed more obliquely
downward than outward (USNM 23494; fig. 56); but their
external ends project backward slightly beyond the level
of the occipital condyles.
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 6
The occipital condyles are relatively large and the
foramen magnum proportionately small. The articular
surfaces of the condyles are more strongly convex from end
to end than from side to side, and are separated ventrally
by a narrow notch. On each side anterior to the correspond-
ing condyle is the lateral knob-like descending process of
the basioccipital, which constitutes the inner wall of the
jugular incisure; the outer wall is contributed by the
exoccipital.
Each postglenoid process extends ventrally about 40 mm.
below the level of the ventral edge of the exoccipital; its
flattened posterior face descends almost vertically.
As regards the posterior aspect of the skull, the contour
of the supraoccipital shield shifts in accordance with the
angle of sight. For example the vertical distance from the
vaginal plate of the vomer to the apex of the supraoccipital
shield on each of the two skulls measures about 200 mm.
By tilting the braincase upward and backward the sub-
triangular outline (drawn by pantograph) of the shield is
accentuated (fig. 56; USNM 23494) as contrasted with
the dorsal flattening when viewed at eye level or almost
horizontally (fig. 55; USNM 16783). It will be noted also
that the convex curvature of the horizontal portion of the
lambdoid crest appears less noticeable in the latter illustra-
tion. Since the ventral border of the right exoccipital is
eroded, the original profile of this edge may be regarded as
slightly conjectural on the skull of the younger individual
(USNM_ 16783). Nevertheless, the exoccipital on this
skull obviously was directed less noticeably obliquely
downward than on the skull of the other individual (fig.
Jo)p
LATERAL view.—The apex of the supraoccipital shield
is the highest point in the dorsal profile and in front of the
latter the dorsal profile of the median intertemporal and
interorbital regions descends obliquely to the base of the
rostrum; the slope of the dorsal profile of the rostrum
from base to extremity is very gradual.
The greatest depth of the rostrum is immediately in
front of the choanae and the depth gradually decreases
toward the distal one fourth where the ventral surface
becomes relatively flat. The outer one half or more of each
maxillary is rather thin throughout its length. The lateral
projection or process of the posteroexternal end of the
maxillary is compressed anteroposteriorly, with the pos-
terior border very thin and the anterior edge thickened;
this process slopes obliquely downward and backward
and terminates at least 25 mm. below the preorbital angle
of the supraorbital process. From this lateral view the
orifices of two or possibly one additional large foramina
can be seen on the internal wall of the maxillary incisure.
The orbital border of the supraorbital process is dor-
soventrally compressed and arched in a fore-and-aft
direction. In front of the rounded preorbital angle, the
UNRECOGNIZED CALVERT CETOTHERE 139
missing lachrymal presumably was lodged between it and
the posteroexternal process of the maxillary, and below
it the jugal was attached by a ligament. The postorbital
projection of the supraorbital process is elongated bringing
its extremity in contact with the anterior end of the zygo-
matic process. The supraorbital process of the frontal
slopes downward from the interorbital region to its orbital
rim, and except for the broad ascending process is not
overlapped by the posterior border of the maxillary.
The rather slender zygomatic process of the squamosal
tapers to its anterior end. The ventral profile of this process
is a uniform curve; the dorsal profile rises gradually behind
the anterior end and merges posteriorly with the abruptly
elevated lambdoid crest on the squamosal.
From a lateral view the postglenoid process extends down-
ward and backward; its posterior face is flattened and its
extremity is compressed anteroposteriorly. Posteriorly the
squamosal is firmly ankylosed to the exoccipital. As seen
from the side the contact of the parietal with the squamosal
is almost horizontal ventrally and nearly vertical posteriorly.
The opposite parietals meet on the midline of the inter-
temporal region to constitute a short isthmus connecting
the occipital portion of the skull with the interorbital region
by overlapping the frontals in a rather broad sutural contact.
Behind the intertemporal region the dorsal edge of the
parietal is overlain by the lateral edge of the supraoccipital
shield, the apex of which extends forward to the level of
the anterior end of the zygomatic process.
The occipital condyle is not visible when the skull is
viewed from the side, since the exoccipital is directed out-
ward and obliquely backward.
In the temporal wall of the braincase, the alisphenoid is
relatively small and is situated posterior to the base of the
supraorbital process and above the pterygoid. The trans-
verse is greater than the vertical diameter of the exposed
outer end of the alisphenoid. The alisphenoid is in contact
with the parietal dorsally and the pterygoid ventrally, but
is separated from the squamosal.
VENTRAL ViIEW.—Neither the type (pl. 49) nor the referred
skull (USNM 23494; pl. 50) has the basicranial region
undamaged. The left half of the basicranium of the type
skull is missing and both pterygoids lack their hamular
processes.
In conformity with the normal construction of a mysticete
skull, the maxillaries constitute most of the palatal surface
of the rostrum (pl. 49, fig. 2). Along the anterior border
the supraorbital process of the frontal is narrowly under-
lapped by the thin plate-like posterior end of the maxillary.
Flattening of the ventral surface of the maxillary is most
pronounced on the outer half and medially is curved down-
ward to conform to the curvature of the trough of the
vomer against which it abuts. A series of shallow, narrow,
275-699—68—4
and slightly curved grooves, the majority being obliquely
directed more forward than outward from their origin near
the midline, serve as channels for the nutrient vessels that
supply the palate and the attached baleen. Somewhat
shorter grooves directed more transversely engrave the
ventral face of each maxillary anterior to the level of the
anterior ends of the palatines. No recognizable pattern or
arrangement of the grooves for the nutrient vessels that
supply the baleen on the palatal surface of the rostrum has
been observed on skulls that represent one or more closely
related species.
The inner edges of the opposite maxillaries diverge on
the ventral surface of the rostrum 510 mm. behind the
distal end of the right maxillary, which terminates 1200
mm. anterior to the posterior end of the vomer. The distance
Ficure 56.—Posterior view of skull, USNM 23494, of Diorocetus
hiatus. For abbreviations, see figure 53.
on the type skull from the anterior end of the right maxillary
to the anterior edge of the optic canal at its point of origin
is 1050 mm.
At the anterior end of the vomer on the type skull (fig. 57)
the opposite maxillaries diverge more noticeably and this
separation continues to their distal ends. To what extent
this divergence is natural and not the result of pressure from
overlying sediments is not readily determinable. On these
two skulls, the premaxillaries do not meet ventrally along
the median longitudinal axis of the rostrum to constitute a
complete floor for the distal portion of the mesorostral
trough.
Divergence of the opposite maxillaries about 130 mm.
in advance of the palatines has exposed the ventral keel of
the vomer as far as its anterior extremity. On the referred
skull (USNM 23494; fig. 58) at a point 200 mm. in front
of the posterior edge of the horizontal vaginal plate, the
vomer develops a flattened ventral exposure, which con-
tinues backward at almost the same horizontal level for a
distance of 85 mm., and then as a continuing thin vertical
partition between the choanae diminishes in height rather
rapidly. The trough of the vomer is widest near the level of
the anterior ends of the palatines. The median vertical
140 UNITED STATES NATIONAL MUSEUM BULLETIN 247
Ficure 57.—Ventral view of skull, USNM 16783, of Diorocetus
hiatus, with left side of cranium and hamular processes of ptery-
goid restored. For abbreviations, see figure 53.
PART 6
partition between the paired choanae is formed by the
vomer and its horizontal posterior plate-like end and is
applied to the ventral surface of the basisphenoid; this
posterior plate also conceals the transverse contact between
the basisphenoid and the basioccipital. Laterally, this
widened plate of the vomer is suturally united with the
corresponding edge of the vaginal process of the pterygoid.
Each palatine (figs. 57, 58) is obliquely truncated pos-
teriorly and extends backward behind the level of the optic
foramen and is suturally united with the pterygoid, which
contributes the missing internally projecting hamular
process. The anterior end of each palatine is rather squarely
truncated and meets the corresponding edge of the adjacent
maxillary; it is also applied to the ventral surface of the
trough-like vomer. The anteroposterior diameter of the
right palatine (USNM 23494) is equivalent to about one
seventh of the total length of the skull.
The immediate region of the optic and sphenorbital
foramina is damaged on both skulls (USNM 16783 and
23494); the alisphenoid on the right side of the type skull
is contiguous to the proximal portion of the optic channel
and may possibly participate in the formation of the pos-
terior border of the foramen.
On both skulls, the distally widened supraorbital process
of the frontal does not extend outward as far as the postero-
external process of the maxillary. The channel for the optic
nerve commences at the optic foramen and curves outward
on the ventral surface of the supraorbital process of the
frontal and increasing in width becomes very wide near the
orbital rim of this lateral process. Near its origin this channel
follows the hinder face of the supraorbital process for a
distance of about 85 mm. and then twists downward
until it is located on the ventral face of this process. The
anterior wall of this optic channel (USNM 23494) is deeper,
but not better defined than the crest along its posterior
limit.
The basioccipital is somewhat rectangular in outline, the
greatest diameter being transverse to its longitudinal axis;
it is ankylosed anteriorly with the basisphenoid, the line of
fusion being overspread by the horizontally expanded
posterior end of the vomer. On each side in front of and
extending laterally beyond the level of the external face of
the occipital condyle (USNM 16783) is a large descending
knob-like protuberance, which is convex on its internal
surface; its external surface is inclined obliquely outward
below the tympanoperiotic recess. The transverse distance
between the inner faces of these protuberances does not
exceed 44 mm. (USNM 23494). The anterior end of each
lateral protuberance is suturally united with the vaginal
process of the corresponding pterygoid and the line of
contact is slightly posterior to the hinder end of the vomer.
The basisphenoid is also a flat rectangular bone, its
greatest diameter being along its anteroposterior axis.
UNRECOGNIZED CALVERT CETOTHERE 141
It is entirely hidden from view by the overspreading
horizontal hinder end of the vomer and is suturally united
laterally with the vaginal process of the pterygoid.
This vaginal process of the pterygoid is preserved on
both sides of the type skull; it meets along its dorsointernal
margin the horizontal exposed hinder end of the vomer.
The posterior end of this vaginal process, as stated previ-
ously, was united with the anterior surface of the lateral
protuberance of the basioccipital. The outer wall of each
internal choana is contributed by the vaginal process of the
pterygoid. This vaginal process and adjoining lateral pro-
tuberance of the basioccipital bound the median region of
the basicranium.
The hamular processes of the pterygoids were not pre-
preserved on either skull; their dimensions, however, are
suggested by the broken edge at the point of origin. Between
the posterior end of the palatine and the bifurcated an-
terior end of the squamosal, which encloses the foramen
ovale, the pterygoid is intercalated. The pterygoid is also
in contact with the ventral surface of the alisphenoid on
the inner wall of the temporal fossa. Dorsally in this fossa
the pterygoid has a narrow contact with the parietal.
Along its entire anterior edge the pterygoid is suturally
united with the palatine, but the posterointernal edge of the
palatine is free. On its outward course the mandibular
branch of the trigeminal nerve follows the groove on the
pterygoid on the roof of the pterygoid fossa.
The rather small pterygoid fossa or sinus is bounded
internally by the vaginal process of the pterygoid, antero-
externally by the downward curving thickened anterior
and external borders of the pterygoid, and to a limited
extend posteroexternally by the short and rather narrow
falciform process of the squamosal. This air-containing
pterygoid fossa is roofed over by the pterygoid, but the
partial ventral cover is reduced. No osseous plate limits this
fossa posteriorly; it is continuous with the tympanoperiotic
recess, which opens into the interior of the cranium. This
recess is bounded by the squamosal and its falciform
process externally, by the pterygoid anteriorly, by the
lateral protuberance of the basioccipital internally and by
the exoccipital posteriorly.
The broad notch or incisure (fig. 58) located at the
posterointernal angle of the tympanoperiotic recess is
bounded by the lateral protuberance of the basioccipital
internally and by the exoccipital externally. This notch
corresponds to the posterior lacerated foramen for the
jugular leash.
Ventrally the contact between the squamosal and the
exoccipital is concealed by the posterior process of the
periotic, which is lodged in a deep groove on the posterior
border of the squamosal. Between this posterior process
and the base of the hinder face of the postglenoid process
is the curved transverse channel for the external auditory
pmx.
\ ‘ant.
Ficure 58.—Ventral view of skull, USNM 23494, of Diorocetus
hiatus. For abbreviations, see figure 53.
142
meatus which increases in width distally. The facial nerve
follows a groove on the ventral face of the posterior process
on its outward course.
The elongated zygomatic process is attenuated toward its
anterior end and is directed obliquely outward and for-
ward. The postglenoid process projects downward at least
50 mm. below the level of the corresponding lateral pro-
tuberances of the basioccipital (USNM 23494). Each
postglenoid process is deflected obliquely backward and
its extremity is compressed anteroposteriorly; its rather
flat posterior face has a shallow dorsoventral concave
curvature. The anterior convex face of this process curves
upward from its ventral margin to its attenuated anterior
extremity. A shallow concavity on the ventral surface of
the squamosal external to the pterygoid fossa extends
from its temporal margin to its sharp-edged posterior
margin, but not outward on the postglenoid articular
surface. Ventrally the squamosal forms the outer and the
major portion of the hinder limit of the temporal fossa.
External to the pterygoid fossa is the large foramen ovale
which is located in the bifurcation between the falciform
and the glenoid portions of the squamosal. The mandib-
ular branch of the trigeminal nerve passes through this
foramen. The maximum anteroposterior diameter of the
foramen ovale is 25 mm., and the maximum transverse
diameter 18 mm. on one skull (USNM 23494). The outer
angles of the exoccipitals project backward slightly be-
yond the posterior articular surfaces of the occipital
condyles.
The crescentic paroccipital processes are transversely
elongated on the ventral edge of the exoccipital external
to the rather broad jugular incisure. A deep narrow groove
separates the occipital condyles medially.
Measurements (in mm.) of skulls are as in column 2.
Tympanic Bulla
No tympanic bullae were associated with the type skull
(USNM 16783). Both bullae, however, although detached
from the periotics on the larger skull (USNM 23494), were
each pressed into the sandy matrix filling the corresponding
tympanoperiotic recess. The skull of Pelocetus calvertensis
(USNM 11976) is considerably larger than this Calvert
skull, but has a much smaller tympanic bulla, its antero-
posterior length (64.5 mm.) being shorter than that (69.5
mm.) of USNM 23494.
The bulla of P. calvertensis (Kellogg, 1965, p. 12, figs. 4a, 4b)
exhibits a somewhat different profile from this Calvert
bulla when viewed from the ventral aspect, its anterior
and posterior ends being obliquely truncated and approxi-
mately equivalent in width. The ventral aspect (pl. 52,
fig. 3) of this bulla (USNM 23494), however, shows a
strong attenuation of the anterior end and a broad (42 mm.)
UNITED STATES NATIONAL MUSEUM BULLETIN 247
Greatest length of skull, anterior end of right
premaxillary to level of posteroexternal
angle of right exoccipital
Distance from anterior end of right premaxil-
lary to posterior articular face of right
occipital condyle
Distance from anterior end of right premaxil-
lary to apex of supraoccipital shield
Length of rostrum, level of posteroexternal
angles of maxillaries to end of right pre-
maxillary
Greatest length of right premaxillary
Distance from apex of supraoccipital shield to
posterior end of right nasal bone
Transverse diameter of skull across posteroex-
ternal angles of supraorbital processes of
frontals
Greatest anteroposterior diameter of extremity
of right supraorbital process of frontal
Transverse diameter of skull across outer sur-
faces of zygomatic processes
Transverse diameter of skull between outer
edges of exoccipitals
Transverse distance between outer edges of
occipital condyles
Greatest or obliquovertical diameter of right
occipital condyle
Greatest transverse diameter of right occipital
condyle
Greatest transverse diameter of foramen mag-
num
Distance from dorsal rim of foramen magnum
to apex of supraoccipital shield
Distance between anterior end of right pre-
maxillary and extremity of right postglenoid
process
Distance between anterior end of left pre-
maxillary and edge of optic channel (groove)
at origin
Greatest breadth of basioccipital across lateral
protuberances, outside measurement
Greatest length of right zygomatic process, ex-
tremity of postglenoid process to anterior end
Distance between opposite foramina ovale
Greatest length of vomer
Greatest anteroposterior diameter of right
palatine
Greatest transverse diameter of right palatine
Distance from posterior surface of right occip-
ital condyle to posterior end of vomer
Distance from posterior surface of right occip-
ital condyle to anterior edge of right
palatine
Posterior edge of vomer to anterior edge of left
palatine
PART 6
USNM USNM
16783 23949
1375+ 1525
1365 1540
1145 1275
1045 1092
1035 1090
115 110
520+ 655
160 180
550+ 635
305+ 370
138+ 144
87 84
50 50
_ 52
215 230
1325 1470
1050 1130
118+ 123
190 245
— 203
720 1005
— 210
_— 118
120 123
450+ 470
305 350
UNRECOGNIZED CALVERT CETOTHERE 143
transversely truncated posterior end; the ventral surface
of the hinder end is also concavely depressed between the
posterointernal and posteroexternal angles and this entire
surface is roughened by numerous pits.
By the usual thin, fragile anterior and posterior pedicles,
this bulla was attached to the periotic. The posterior pedicle
arises internally from the posterior end of the involucrum
and externally from the posterior end of the thin outer lip;
on the right bulla this pedicle was separated from the low,
blunt posterior conical apophysis by a short crease.
The narrow epitympanic recess or tympanic cavity of the
bulla (pl. 52, fig. 2) is bounded externally by the brittle,
thin overarching outer lip and internally by the transversely
sparsely creased involucrum. The width of this tympanic
cavity decreases toward the anterior or eustachian outlet.
This thin outer lip is supported in front of the sigmoid
process by the slender anterior process, which is ankylosed
to the periotic near the epitympanic orifice of the Fallopian
canal.
The rounded and thickened extremity of the sigmoid
process is twisted at right angles to the longitudinal axis
of the bulla, its anterior face convex and its posterior face
deeply concave. A deep cleft separates the sigmoid process
from the adjacent posterior conical apophysis of Beauregard.
The malleus, which was attached to the outer lip of the
bulla by its slender stalk-like anterior process along the
anterior border of the sigmoid process, is broken off and
lost.
Viewed from the external side (pl. 52, fig. 4) the ventral
profile is arched, the anterior obliquely truncated and the
posterior convex. Viewed from the dorsal aspect, the
involucrum attains its maximum width behind the middle
of its length.
Measurements (in mm.) of the left tympanic bulla
(USNM 23494) are as follows:
Greatest length of tympanic bulla 69.5
Greatest width of tympanic bulla 48.5
Greatest vertical diameter on external side, ventral face 60.5
to tip of sigmoid process
Greatest length of tympanic cavity 54
Periotic
On the referred skull (USNM 23494) the posterior proc-
esses of both periotics (pl. 50, fig. 2) are firmly lodged in
the broad groove between the exoccipital and the post-
glenoid portion of the squamosal. The right periotic was
detached from this skull for illustration and description. A
broad deep groove (pl. 51, fig. 4) extends along the ventral
face of the posterior process from the outer margin of the
fossa for the stapedial muscle to the external end of this
process. In recent mysticetes the facial nerve occupies this
groove on its outward course. The anterior process (pro-otic)
is strongly compressed from side to side, relatively deep
anteroposteriorly, and has an emarginate anterior border.
This transversely compressed anterior process is lodged in
the deep excavation in the squamosal external to and
behind the pterygoid fossa. The basal portion of the very
thin side-to-side compressed anterior pedicle of the tympanic
bulla is ankylosed to the ventral surface of the pars laby-
rinthica 12 mm. anterior to the epitympanic aperture of the
Fallopian aqueduct. The base of the posterior pedicle of
the bulla was fused to the anterointernal angle of the ventral
surface of the posterior process of the periotic in front of
the broad groove for the facial nerve.
A broad concave fossa (vertical diameter, 6 to 15 mm.;
length, 33 mm.) extends from the deep concave excavation
at the posterointernal angle of the posterior process (opis-
thotic) inward across the posterior face of the pars cochlearis
above (dorsal to) the foramen rotunda and its projecting shelf
to the inner or cerebral face of the periotic. Ventrally this
fossa is separated from the fossa for the stapedial muscle by
the thin crestlike posterior ridge bounding the latter and
internally is directed upward and inward at a right angle
to this fossa. Dr. Francis C. Fraser and P. E. Purves (in
letter) suggest that this depressed smooth surface may be
attributed to an extension of the air sac system.
From a tympanic view (pl. 51, fig. 4) the fenestra ovalis
is largely hidden by the overhanging external face of the
pars cochlearts. A very thin rim separates the fenestra ovalis
externally from the groove for the facial nerve and posteri-
orly from the fossa for the stapedial muscle. A narrow groove
extends forward and inward from the fenestra ovalis between
the pars cochlearis and the anterior process. The fossa for the
stapedial muscle is broader than long and extends down-
ward on external face of pars cochlearis and to a limited
extent on internal end of the posterior process.
A rather shallow concavity for reception of the head of
the malleus is situated on ventral face of the anterior
process external to and for the most part anterior to the
epitympanic orifice of the Fallopian aqueduct. The fossa
incudis is a small shallow pit on the denser outer portion
of the periotic external to the channel for the facial nerve.
The pars cochlearis is relatively small; its crown is not
noticeably enlarged or extended ventrally. On one periotic
(USNM 23494) an anteroposterior crease divides the ven-
tral face of the pars cochlearis into a convex elevated external
portion and a broader internal surface that extends to the
rim of the internal acoustic meatus; this crease extends less
than halfway backward toward the fenestra rotunda on the
other periotic (USNM 16783).
The cerebral face of the pars cochlearis (labyrinthic region)
is relatively small, irregular in outline, and the region
dorsal to the internal acoustic meatus is ornamented either
with contiguous shallow concavities of variable size, and
144 UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 6
ane
Ficure 59.—Views of left mandible, USNM 23494, of Diorocetus hiatus: a, external view; 6, dorsal view; c, condyle. Abbrs.: an., angle;
cm., condyle of mandible; cor., coronoid process; f.g., gingival or alveolar foramen; f.m., mental foramen; ipt., groove for attachment
of internal pterygoid muscle.
irregularly spaced (USNM 23494; pl. 51, fig. 3) or porous
and rugose (USNM 16783). The internal acoustic meatus
at the level of the cerebral rim is either circular or
ovoidal; the rim is less than 8 mm. distant from the longi-
tudinal crease on the pars cochlearis. The cerebral aperture
of the Fallopian aqueduct (pl. 51, fig. 3) is either adjacent
to the rim of the internal acoustic meatus, but having a
supplemental anterior opening at the anteroexternal angle
of the pars cochlearis (USNM 23494), or limited to the
single anterior opening (USNM 16783) present on the pre-
ceding periotic. The vestibular aqueduct opens into a deep
ovoidal depression on the cerebral face behind and above
the internal acoustic meatus. The small orifice of the cochlear
aqueduct is situated ventral to the vestibular aqueduct.
Measurements (in mm.) of the periotics, USNM 16783
and 23494, area as follows:
USNM USNM
23494 16783
Right Right
Length of posterior process, distance from 89 96
external wall of stapedial fossa to extremity
Greatest dorsoventral diameter of periotic 42 44
from most inflated portion of tympanic face
of pars cochlearis to most projecting point on
cerebral face
Distance between epitympanic orifice of 44 40
aquaeductus Fallopii and extremity of anterior
process
Distance from external end of posterior process 130 115
to anterior end of anterior process (in a
straight line)
Mandibles
The epiphyses of most of the vertebrae accompanying
the two skulls and their associated mandibles were not
ankylosed to the centra and hence these two cetotheres
were not physically mature. Although fractured prior to
excavation both of the mandibles associated with the
larger skull (USNM 23494) have been restored essentially
to their original appearance. Both of the mandibles associ-
ated with the smaller skull (USNM 16783) are complete
except for the condyle and a portion of the ramus behind
the coronoid process. The description will be based mainly
on the larger mandibles.
The right mandible of Miocene (Anversian) Belgian
Mesocetus pinguis (MHNB 13) is larger than the Calvert
right mandible (USNM 23494), its measurements being:
length, 1642 mm.; vertical diameter at distal end, 123
mm.; and transverse diameter at same point, 39.5 mm. The
corresponding measurements of the right mandible of the
larger Calvert cetothere are respectively, 1485, 99 and 36
mm.
Except for a noticeable flattening of the anterior one
fourth of the internal surface, the internal and external
faces of the larger pair of mandibles (USNM 23494) have
a dorsoventral convex curvature, more especially on the
posterior half of their length, in contrast to the much less
obvious convexity of the internal faces of the mandibles
of the smaller individual (USNM 16783). The internal
and external surfaces of the horizontal ramus meet ven-
trally to form a low ridge which anteriorly tends to ap-
proach the internal face. All four mandibles are slightly
UNRECOGNIZED CALVERT CETOTHERE
bowed outward (fig. 59b); the lengths (1485 and 1487
mm.) of the larger pair (USNM 23494) exceed slightly
the distance from the glenoid articular face of the post-
glenoid process to the extremity of the corresponding
premaxillary (1470 mm.).
For a distance of 540 mm. in front of the apex of the
coronoid process, the dorsal border of the horizontal ramus
is abruptly transversely compressed to constitute a thin
longitudinal ridge. This ridge limits the direction of the
small internal nutrient foramina, each of which at the
posterior end of this series opens into a short antero-
obliquely directed groove; these grooves increase in length
and progressively shift to a more forward direction. This
longitudinal series of small nutrient foramina make their
appearance on the internal surface of the ramus below but
near the level of the ridgelike dorsal edge. These small
foramina begin proximally on the internal surface of the
ramus a short distance (80 mm.) in front of the apex of the
coronoid process and gradually rise to the dorsal edge
anteriorly, those of the anterior extremity opening into a
long anteriorly directed narrow groove on the dorsal edge.
This anteriormost long (160 to 180 mm.), narrow groove
(fig. 59b) on the dorsal edge (USNM 23494) originates in
an anteriorly directed foramen, which represents the ter-
minal one of the series of small foramina that move up to
the dorsal edge of the ramus.
The most posterior mental foramen (fig. 59a) on the
external surface of the ramus is located 490 mm. anterior
to the posterior articular face of the condyle on both
mandibles (USNM 23494). Ten large external mental
foramina are visible on the right mandible of the large
individual and eight on the other right mandible (USNM
16783); all of these foramina open into an anteriorly
directed groove of variable length, a few as long as 50 mm.,
and are located below the ridgelike dorsal edge. Most of
these grooves increase in width from the orifice to the point
where they merge with the external surface or disappear.
These mental foramina do not drop down to a lower level
at the anterior end of the mandible. A large terminal
mental foramen is present below the dorsal edge at the
anterior end of the mandibles of the smaller individual
(USNM 16783), but is closed on the mandibles of the
larger individual.
Viewed from the side the ventral profile of the mandible
is slightly bowed upward between the level of the apex of
the coronoid process and the commencement of the anterior
third of the horizontal ramus. The dorsal edge of the
anterior ends of both large mandibles is broader than the
ventral edge. On all four mandibles the symphysis was
unquestionably short since no noticeably roughened area
is present. Above the ventral edge of this anterior portion
and below the short longitudinal crease, the lower border
145
(measuring 37 mm. dorsoventrally) of the internal face of
the ramus is depressed.
The small coronoid process is low, subtriangular, ter-
minating in a blunt everted apex, concave internally and
convex externally, the posterior edge being slightly thinner
than the anterior edge. The coronoid process is bent out-
ward and backward above and anterior to the entrance
to the large mandibular canal.
The condyle (fig. 59c) on the mandibles of the larger
individual (USNM 23494) is large, expanded from side to
side at the middle of its vertical diameter, moderately
convex, bounded ventrally on the internal face of the ramus
above the angle by the deep groove for attachment of the
internal pterygoid muscle. On both mandibles this groove
terminates at the posterior end of the ramus and does not
extend across the posterior face of the condyle. Dorsally
the condyle is abruptly compressed and bent inward to
conform with the curvature of the thin rim of the horizontal
ramus behind the coronoid process. The greatest transverse
diameter of the condyle on the left mandible is 89 mm. and
the vertical diameter of the condylar end of the ramus is
175 mm. The forward curving external border of the
condyle projects noticeably beyond the lateral surfaces of
the adjacent portion of the ramus. The transverse diameter
of the well-developed angle is 43 mm. The posterior surface
of the condyle is 225 mm. distant from the center of the
apex of the coronoid process on both of the larger mandibles.
Recent mysticetes have the thick fibrous pad, which covers
the condyle, connected with the glenoid fossa of the zygo-
matic process (Turner, 1892, p. 69; Schulte, 1916, p. 483).
A similar fibrous pad would be needed for attachment of
these heavy Calvert mandibles.
Of the several Miocene (Anversian) mandibles illustrated
by Van Beneden, the profile of the posterior aspect of the
condyle of the right mandible of Mesocetus pinguis (MHNB
13; Van Beneden, 1886, pl. 44, fig. 10) resembles most
closely that of this left mandible (USNM 23494). The
external border of the condyle of M. pinguis is eroded on
its ventral half, but this condition does not mask the original
indentation of that profile at the level of the opposite
internal groove. The Calvert mandibular condyle lacks
this indentation. The condyle of the Calvert mandible
(fig. 59c) is slightly smaller, the greatest transverse diameter
(89 mm.) being less than that (96.5 mm.) of the Belgian
cetothere while its vertical diameter (175 mm.) exceeds
that (164 mm.) of the latter. On both of these mandibles
the greatest width is above the middle of the vertical height
of the condyle.
As will be noted on consulting the table of measurements,
distortion resulting from crushing and fracturing has
affected to a varying extent the vertical and transverse
dimensions of the horizontal ramus of opposite mandibles
146
belonging to the same individual. Furthermore, twisting
of the left mandible of USNM 23494 has resulted in the
inward deflection of the ventral border of the anterior one
third of the horizontal ramus (fig. 59b).
Relatively few mandibles with attached condyles have
been recovered from the Calvert formation. Three recog-
nizable types of condyles are represented, the most obvious
distinguishing characteristics of each of these being as-
sociated with the groove for the attachment of the internal
pterygoid muscle. Three variants of one type have been
noted. That these variants may possibly be attributed to
differential growth has not as yet been excluded with
certainty.
Measurements (in mm.) of mandibles are as in column 2.
Vertebrae
Associated with the skull (USNM 23494) of the larger
individual were one cervical, five dorsal, eleven lumbar,
and five caudal vertebrae. Ankylosis of the epiphyses to
the centra proceeded rather irregularly in this vertebral
series. The anterior epiphysis is attached to one middle
and one posterior dorsal, to two middle and one posterior
lumbar, and to one middle caudal. Ankylosis of the epi-
physes to the centra in Recent mysticetes normally proceeds
forward from terminal caudals and backward from the
axis until this process is completed near the middle of the
vertebral series at physical maturity. Alongside the smaller
skull (USNM 16783) were found an axis, two posterior
cervical and the first dorsal vertebrae. The posterior
epiphysis is attached to the centrum of the last cervical,
both epiphyses of the sixth cervical and the first dorsal
were detached and lost. The total length of the skeleton
(USNM 23494), from the extremity of the rostrum to and
including the terminal caudal, apparently did not exceed
eighteen feet. This estimate is based on vertebrae of com-
parable size selected from incomplete skeletons of several
individuals to assemble a consecutive series of cervical,
dorsal, lumbar, and caudal vertebrae. All of these verte-
brae were excavated in zones 11 to 14 of the Calvert
formation of Maryland.
CERVICAL VETEBRAE.—None of the cervical vertebrae
were ankylosed to preceding or succeeding vertebrae.
The axis lacks a neural spine; the odontoid process is low
and blunt; the moderately elongated transverse processes
are directed outward, but not strongly backward. Con-
tour of anterior face of centrum of sixth cervical is broadly
elliptical; pedicles of neural arch are low; no vestige
of a ventral transverse process is present. Contour of
anterior face of centrum of seventh cervical is subelliptical
(USNM 16783) or subquadrate (USNM 23494); attenu-
ated diapophysis directed outward and slightly forward;
no vestige of a ventral transverse process is present. The
UNITED STATES NATIONAL MUSEUM BULLETIN 247
Greatest length of mandible
in straight line when
complete, estimated
Greatest length of mandible
as preserved in a straight
line
Greatest length of mandible
as preserved along outside
curvature
Distance from anterior end
to level of center of coro-
noid process along outside
curvature
Greatest vertical diameter
100 mm. behind anterior
end of ramus
Greatest transverse diam-
eter 100 mm. behind
anterior end of ramus
Greatest vertical diameter
300 mm. behind anterior
end of ramus
Greatest transverse diam-
eter 300 mm. behind
anterior end of ramus
Greatest vertical diameter
500 mm. behind anterior
end of ramus
Greatest transverse diam-
eter 500 mm. behind
anterior end of ramus
Greatest vertical diameter
700 mm. behind anterior
end of ramus
Greatest transverse diam-
eter 700 mm. behind
anterior end of ramus
Greatest vertical diameter
900 mm. behind anterior
end of ramus
Greatest transverse diam-
eter 900 mm. behind
anterior end of ramus
Greatest vertical diameter
through coronoid process
Greatest vertical diameter
through hinder end in-
cluding condyle
Horizontal distance be-
tween center of coronoid
process and hinder face
of condyle
Greatest transverse diam-
eter of condyle
USNM 16783
Right Left
1330+ 1330+
1242 1151
1270 1190
1140 1135
91 87
33 31
80 81
40 32
88 86
48 37
85 82
48 42
88 80
52 53
128 131+
PART 6
USNM 23494
1485 1487
1485 1487
1498 1500
1280 1275
99 98
36 38
o5 oD
52 51
99 102
59 59
104 107
68 72
99 104
72 74
ey 165
176 175
235 240
&6 89
UNRECOGNIZED CALVERT CETOTHERE 147
estimated length (270 mm.; 10% inches) of the seven
consecutive cervical vertebrae is based on vertebrae of
comparable size of several individuals from the Calvert
formation of Maryland.
Axis: Characterized in part by the short blunt odontoid
process. Transverse processes (pl. 53, fig. 1) moderately
elongated, dorsoventrally widened distally, directed out-
ward, but not appreciably backward. Foramen transver-
sarium in transverse process for cervical extension of the
thoracic retia mirabilia large, but not inclosed by bone
dorsally; a large deep concavity on the posterior face of this
process encircles this transverse foramen. The greatest
width (63 mm.) of the neural cana! exceeds its height
(53 mm.). The rather large anterior facets for articulation
with the atlas are more flattened than depressed, the vertical
diameter (84 mm.) of each equivalent to more than half
of the transverse width (156 mm.) of the combined anterior
articular surfaces. The odontoid process is broad, low, and
concave below its most projecting piont. The anterior
median portion of the neural arch is broad, truncated
transversely, and is extended forward beyond the level of
the anterior articular facets to articulate with or rest on
the opposing surface of the neural arch of the atlas. The
neural spine is not developed; the neural arch is broad and
has a deep central notch on the posterior portion of the
thickened roof. The floor of the neural canal is shallowly
concave; the flat ventral surface of the centrum is almost
horizontal. The broad (113 mm.) posterior face of the
centrum is deeply concave. The greatest width of the
axis is 255 mm. and its greatest vertical diameter 136 mm.
Szxth Cervical: ‘The contour of the anterior face of the
centrum of this sixth cervical (USNM 16783) is broadly
elliptical, its transverse diameter (96 mm.) being greater
than its vertical (68 mm.). The pedicles (left, minimum
anteroposterior diameter, 9 mm.) of the neural arch are
low, and provide the major support to each diapophysis
by their location on the dorsoexternal surface of the cen-
trum. The minimum dorsoventral diameter of the left
pedicle is 34 mm. and the greatest width of the neural canal
is 76 mm. Both diapophyses are broken off at the base
and the roof of the neural arch, the zygapophysial facets
and the neural spine are missing. No vestige of the lower
transverse process or parapophysis persists.
Seventh Cervical: Iwo incomplete vertebrae represent
the seventh in the cervical series. The anterior face of the
centrum of the smaller one (USNM 16783) is subelliptical
and the other one (USNM 23494) is subquadrate. No
median longitudinal keel is developed on the ventral face
of either centrum, but this may be attributed to immaturity.
The pedicles of the neural arch are continuous with the
broad anteroposteriorly compressed basal portions of the
diapophyses which project outward from the dorsal antero-
lateral angles of the centrum. Each diapophysis is abruptly
increased in depth near the base, attenuated toward its
extremity, directed outward and slightly forward; the
terminal articular facet is barely developed. The prezyg-
apophysial facets are narrow and elongated. Measure-
ments of the larger cervical (USNM 23494; pl. 53, fig. 2)
are as follows: Transverse diameter of anterior face of
centrum, 92 mm.; vertical diameter of anterior face of
centrum, 66 mm.; greatest transverse diameter of neural
canal, 80 mm.; greatest distance between outer ends of
diapophyses, 244 mm.
DorsaL VERTEBRAE.—The second to sixth dorsal
vertebrae inclusive are not represented among the vertebrae
associated with the two skulls (USNM 16783, 23494).
At the anterior end of the dorsal series the centrum is
subelliptical in outline anteriorly, that of the seventh sub-
cordate and then the contour is progressively altered to
elliptical. Posteroexternal demifacets for the capitulum of
the following rib were present on the lateral surfaces of the
centrum of the first and seventh dorsals but not on succeeding
vertebrae. The neural canal decreases in width from the
first to the eighth dorsal; behind the eighth dorsal the
vertical diameter of the neural canal increases. The pedicles
of the neural arch of the seventh dorsal are massive and
widened transversely. The thickened diapophyses arise
from the pedicle of the neural arch, which is located on the
first to eighth dorsals on the dorsoexternal portion of the
centrum anteriorly. The parapophyses of the ninth to
twelfth dorsals, inclusive, project outward horizontally
from the lateral surface of the centrum. The width of the
gap between the prezygapophysial facets decreases from
the anterior to the posterior end of the dorsal series. Behind
the eighth dorsal vertebra, the anteroposterior crest de-
limiting the outer edge of the prezygapophysial facet
increases in prominence as the metapophysis is shifted from
horizontal to vertical. These side-to-side compressed
metapophyses progressively increase in size and rise higher
above the level of the floor of the neural canal.
Dorsal vertebrae belonging to several individuals of
comparable size, all derived from the Calvert formation of
Maryland, were substituted for the missing anterior
dorsals (first to sixth) in one series (USNM 23494) in order
to estimate fairly accurately the length of a consecutive
series of twelve dorsal vertebrae as 870 mm. (34¥ inches).
First Dorsal: In dimensions the centrum of the first
dorsal (USNM. 16783; pl. 53, fig. 3) differs from the seventh
cervical only in the slight reduction of the vertical diameter
of the subelliptical anterior face (62 mm. from 70 mm.).
The roof of the neural arch, the neural spine and the
zygapophysial facets are missing. The attenuated dia-
pophyses are anteroposteriorly compressed, dorsoventrally
widened, as well as concavely depressed anteriorly on the
basal half. Each diapophysis, which projects outward and
strongly forward, is combined at the base with the pedicle
148
of the neural arch. The distal end of each diapophysis is
obliquely truncated in a dorsoventral direction, the flat
surface serving as the articular facet for the head of the
first rib. The greatest distance between outer ends of
diapophyses is 215 mm. The dorsoventrally elongated
demifacet for reception of the capitulum of the second rib
is located dorsally on the posteroexternal angle of the
centrum.
Seventh Dorsal: On this dorsal (USNM 23494; pl. 55,
fig. 3) each metapophysis consists of a ridgelike crest which
forms the external limit of the prezygapophysial facet; this
concave facet extends backward beyond the base of the
neural spine anteriorly. Each broad, but dorsoventrally
thickened transverse process (diapophysis) projects out-
ward from the transversely widened (32 mm.) pedicle of
the neural arch located on the dorsoexternal portion of the
centrum; it is bent very slightly upward, but is extended
forward barely beyond the level of the anterior face of the
centrum. The greatest distance between outer ends of
diapophyses is 153 mm. The facet for the tuberculum of
the seventh rib on the extremity of each diapophysis is
elongated (length 40 mm.), subcrescentic in outline, and
deeply concave medially. The postzygapophysial facets are
eroded. The neural spine (minimum width, 50 mm.) is
incomplete, but is slanted backward. The neural canal is
wide (48 mm.) and rather low (21 mm.) and is quite unlike
that of the ninth dorsal. The contour of the anterior face
of the centrum is subcordate. A reduced posteroexternal
demifacet for articulation with the capitulum of an eighth
rib is present on the right posterodorsal angle of the centrum.
Ninth Dorsal: The accentuation of the low anteropos-
terior crest has now culminated in the shift of the meta-
pophysis from horizontal to vertical. This development
permits the pair of metapophyses (USNM 23494; pl. 54,
fig. 6) to clasp more firmly the backward projecting post-
zygapophyses for the preceding dorsal. Each metapophysis
is compressed from side to side, obtusely pointed antero-
dorsally, extended forward beyond the level of the anterior
face of the centrum and constitutes the outer wall of the
narrow concave prezygapophysial facet. The transverse
diameter of the neural canal (50 mm.) exceeds the vertical
(42 mm.) anteriorly. On the first eight dorsals, inclusive, of
Calvert cetotheres the transverse process (diapophysis)
projects outward mainly from the more or less massive
pedicles of the neural arch and maintains its elevation
above the dorsal face of the centrum. On the ninth dorsal
(pl. 55, fig. 1) the broad transverse process (parapophysis)
projects outward from the dorsoexternal surface of the
centrum. The ventral face of the extremity of this process
is strongly concave; it ends in an elongated facet (length,
60 mm; vertical diameter, 12 mm. posteriorly and 6 mm.
anteriorly) for the head of the ninth rib. The distance
between the ends of the parapophyses is 199 mm., and
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 6
this distance progressively increases to the end of the dorsal
series. The postzygapophyses are destroyed. The neural
spine, which rises 102 mm. above the roof of the neural
canal, tapers from its base to its truncated extremity. The
pedicles of the neural arch are quite thin (minimum
transverse diameter, 6 mm.); the minimum length of each
is 45 mm.
Tenth Dorsal: Longer, horizontally widened, and dorso-
ventrally compressed transverse processes (parapophyses)
and a slightly narrower neural canal distinguish this dorsal
(USNM 23494; pl. 55, fig. 2) from the ninth dorsal. Each
broad parapophysis projects horizontally outward from
the upper portion of the lateral surface of the centrum.
The posterior end of the distal facet on this process for the
head of the tenth rib is thicker (16 mm.) than the anterior
end (5 mm.); the anteroposterior diameter of this facet is
59 mm. The thin pedicles of the neural arch have a slightly
greater anteroposterior length (49 mm.) than on the ninth
dorsal. The vertical diameter (43 mm.) of the neural canal
equals the transverse (43 mm.) diameter. The large meta-
pophyses (pl. 54, fig. 3) project forward nearly horizontally
beyond the level of the anterior face of the centrum; they
rise 53 mm. above the level of the floor of the neural canal.
The prezygapophysial facets are poorly defined and the
postzygapophysial facets appear to be nonexistent. The
contour of the anterior face of the centrum is subcordate.
Eleventh Dorsal: Long, rather wide, dorsoventrally com-
pressed parapophyses projecting horizontally outward
from the lateral surface of the centrum characterize this
dorsal (USNM 23494; pl. 54, fig. 7). The anterior edge
of each parapophysis is thin and the posterior border
thickened; the main area of attachment of the eleventh
rib seems to have been on the posterior two-thirds of the
distal end. The distance between the ends of the para-
pophyses is 280 mm. The thin pedicles (pl. 54, fig. 4) of
the neural arch are slightly longer (53 mm.) than those on
the tenth dorsal. The metapophyses as well as the pre-
and post-zygapophysial facets and minor portions of the
neural arch are missing. No reduction in the dimensions
of the neural canal is as yet evident, the vertical diameter
(45 mm.) being slightly greater than the transverse diam-
eter (42 mm.). The contour of the anterior face of the
centrum is more elliptical than subcordate.
Twelfth Dorsal: The roughened truncated end of the
broad elongated parapophysis indicates the area of attach-
ment of the twelfth rib. Both parapophyses lack portions
of the anterior border which was quite thin in contrast
to the thickened and rounded posterior border. The dis-
tance between the ends of the parapophyses (USNM
23494; pl. 54, fig. 8) is 335 mm. Each parapophysis (pl.
55, fig. 4) projects outward from the lateral surface of the
centrum; the posterior edge tends to bend backward
toward the extremity. The thin pedicles of the neural arch
UNRECOGNIZED CALVERT
USNM 23494-Dorsal Vertebrae
Anteroposterior diameter of centrum
Transverse diameter of centrum anteriorly
Vertical diameter of centrum anteriorly
Minimum anteroposterior length of pedicle of neural arch
Transverse diameter of neural canal anteriorly
Vertical diameter of neural canal anteriorly
Distance between ends of transverse processes
Dorsal edge of metapophysis to ventral face of centrum anteriorly
Tip of neural spine to ventral face of centrum posteriorly
CETOTHERE 149
D.1 D.7 DI D.10 D.11 D.12
33° 63? 72% 78% 90 92
93 83 86 90 88 91
62 62 67 67 7\ 73
15 43 45 49 53 53
70 48 50 43 42 39
— 21 42 43 45 43
215 153 199 220+ 280 335
— 85 113 121 128+ 128
— 197 200 205+ 206+ 215
a—Anterior epiphysis missing. += Both epiphyses missing. »= Posterior epiphysis missing.
are damaged. The neural spine is eroded at its extremity
and is slanted backward. The transverse diameter (39
mm.) of the neural canal has decreased. The antero-
posterior diameter of the centrum apparently did not
exceed the transverse diameter of the anterior face (91
mm.); the contour of the anterior face is elliptical.
Measurements (in mm.) of dorsal vertebrae, USNM
23494, are as indicated above.
’ LUMBAR VERTEBRAE.—The processes of all eleven lumbar
vertebrae (USNM 23494) are damaged and more or less
incomplete. For this reason the lumbar vertebrae will not
be described individually. Descriptive comments will be
restricted to the successive alterations observable from the
anterior to the posterior end of this series. The epiphyses
of all the lumbars were detached from the centra when
excavated. The ventral median longitudinal keel is not
developed on the first and second, but is quite distinct
on the fourth lumbar and persists to the eleventh. Arranged
in serial sequence the increase in the length of the centrum
from the first (86+ mm.) to the eleventh (113-4 mm.) is
more noticeable than the increase in the minimum antero-
posterior diameter of the thin pedicle of the neural arch
(from 53 mm. to 57 mm.). There is an increase in the
USNM 23494-Lumbar Vertebrae L.1 L.2
Anteroposterior diameter of centrum 86? 89?
Transverse diameter of centrum anteriorly 89 92
Vertical diameter of centrum anteriorly 74 79
Minimum anteroposterior length of pedicle of 54 53
neural arch
Transverse diameter of neural canal anteriorly 40 44
Vertical diameter of neural canal anteriorly 48 45
Distance between ends of transverse processes 325 —
Dorsal edge of metapophysis to ventral face of 142 =
centrum anteriorly
Tip of neural spine to ventral face of centrum 182+ 204+
posteriorly
minimum anteroposterior diameter of the transverse
process from the second (48 mm.; pl. 55, fig. 7) to the
eleventh lumbar (68 mm.) and a decrease in its length
(the distance between the outer ends of the parapophyses
reduced from 330 to 265 mm.). The width of the neural
canal diminishes from the first (40 mm.) to the eleventh
lumbar (22 mm.; pl. 55, fig. 6), and there is an imperceptible
decrease in the vertical diameter of the neural canal from
the first (44 mm.) to the eleventh (41 mm.). The elongated
thin lamina-like metapophyses are large processes that
project upward and forward from the neural arch beyond
the level of the anterior face of the centrum and are inclined
obliquely outward from the ventral to the dorsal edges.
They do not embrace closely the narrow backwardly
projecting dorsal portion of the neural arch of the preceding
lumbar. The gap between the metapophyses is gradually
reduced from the first lumbar to the eleventh. Viewed from
the side, the neural spines are inclined slightly backward.
This estimate of the length (1300 mm.; 51 inches) of twelve
lumbar vertebrae is based on eleven of one individual
(USNM 23494).
Measurements (in mm.) of lumbar vertebrae, USNM
23494, are as indicated below.
Ibpgh Loi SO EO mePlEs/A L.8
QS Cee 1} 103 §1Gs 110
Si O3: 96 96 101 100
L9 L.10 L.11
98> 118 113?
104 105 110
81 86 84 85 87 92 91 96 100
= 55 = 53 48 50 51 51 57
40 39 39 40 37 35 33 29 22
= 42 ae 45 40 42 42 = 4]
= gsi0a = = Wp = Bsr A war
— ie == 114 4s 149 148 = 161
—= Isr = = AO = ABse = ==
«—Anterior epiphysis missing. >= Both epiphyses missing. »= Posterior epiphysis missing.
150
CAUDAL VERTEBRAE.—Eleven caudal vertebrae and de-
tached epiphyses of another (USNM 16567), which were
associated with one chevron when excavated, are re-
ferred to the same species as the five caudal vertebrae
(USNM 23494) found intermingled with other skeletal
elements alongside the larger skull. Except for one middle
caudal which has the anterior epiphysis attached to the
centrum, the epiphyses are detached on the remaining
four caudals in one series (USNM 23494). Two anterior
caudals (third and fourth) and one middle caudal (seventh)
have the anterior epiphysis and three (second, fourth, and
sixth) have the posterior epiphysis fused with the centrum
\ _=—S—_=—
Ale;
ef
\
Ficure 60.—Views of second caudal, USNM 16567, of Diorocetus
hiatus: a, anterior view; 4, lateral view. Abbrs.: mp., meta-
pophysis; tr., transverse process.
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 6
in the other series (USNM 16567); the remaining epiphyses
were detached.
At the anterior end of the caudal series, the centra are
relatively massive as contrasted with the posterior lumbars,
but are progressively shortened from the second to eighth;
the neural spine and the neural canal diminish in height
from the second to the eighth; the interval between the
dorsal edges of the opposite metapophyses progressively
increases from the second to the sixth or seventh; and the
horizontally outward directed transverse processes become
reduced gradually to a flange-like process on the seventh
caudal.
On the centrum of the posteriormost lumbar (USNM
23494) there is a single sharply defined median longitudinal
ventral ridge; this ridge is replaced by a pair of parallel
ridges on the first caudal. The width of the median ventral
longitudinal haemal groove between the haemal tubercles
(hypapophyses) increases gradually to the fourth or fifth
caudal (USNM 16567). The anterior pair of haemal
tubercles are not developed on the three anterior caudals.
The posterior pair of haemal tubercles increases in size
from the third to the sixth; concomitantly the distance
between the anterior and the posterior tubercles on each
side is decreased. These posterior haemal tubercles certainly
are attached to the chevron bone on the third caudal.
On the third, fourth, and fifth caudals, the oblique upward
course of the segmental blood vessels from the haemal
groove to the anterior basal edge of the transverse process
and thence to the posterior end of the neural canal is
indicated by a faint shallow groove. This groove becomes
more distinct on the left side of the sixth caudal; the blood
vessels perforate the reduced transverse process on the right
side of the sixth, both sides on the seventh and eighth
caudal and the lateral face of the centrum on the ninth
caudal, The caudals behind the last (ninth) to which the
chevrons are attached lack a roof over the neural canal;
these centra are pierced by vertical canals from the ventral
face to the dorsal neural depression on one series. In the
centra of these terminal caudals (USNM 16567) these
vertical canals have three openings on the ventral face of
the centrum and two on the dorsal face. These vertical
canals in the centra of the ninth and following posterior
caudal vertebrae provide a passage for blood in the branches
of the caudal artery and vein between the haemal groove
and the neural canal.
Although no complete consecutive series of caudal
vertebrae is now at hand, one may infer with reasonable
certainty that fourteen caudals comprise this portion of the
vertebral column. This inference is based on series of
caudals belonging to five individuals that duplicate one
another in part as well as containing one or more caudals
missing from otherwise consecutive vertebrae. The eleven
UNRECOGNIZED CALVERT CETOTHERE 151
caudals comprising the most complete series (USNM 16567)
indicate a total length of 1530 mm. (60 inches) for a series
of 14 and for the series associated with the skull (USNM
93494) as 1425 mm. (56 inches).
First Caudal: This vertebra is not represented among the
caudals in the collection.
Second Caudal: Low, closely approximated parallel longi-
tudinal ventral ridges (pl. 56, fig. 1) bound the shallow
haemal groove (minimum width, 10 mm.), which separates
the pair of posterior flattened protuberances for articulation
with a chevron (USNM 16567); these protuberances are
partially eroded and their true function is inferred.
The transverse processes are broad (minimum antero-
posterior diameter, 68 mm.), short and squarely truncated
(fig. 60b) at extremity; they project outward and slightly
downward.
The neural canal (fig. 60a) is high and narrow, its height
(44 mm.) being equivalent to twice its width (22 mm.).
The metapophyses slope obliquely upward from the ventral
to the dorsal margin and apparently projected forward
barely beyond the level of the anterior face of the centrum.
Although damaged the neural spine is shorter than that
of the last lumbar, with a marked backward slope. The
width (117 mm.) exceeds the vertical diameter (106 mm.)
of the anterior face of the robust centrum.
The second caudal in the other series (USNM 23494)
agrees with the above described caudal in having a wide
backward slanting neural spine, high (41 mm.) and narrow
(21 mm.) neural canal, broad truncated transverse processes,
and a narrow ventral longitudinal haemal groove.
Third Caudal: This caudal (USNM 16567) is charac-
terized chiefly by an increase in the width of the ventral
longitudinal haemal groove, more prominent posterior
haemal tubercles (pl. 56, fig. 2), but as yet undeveloped
anterior haemal tubercles and less elevated metapophyses.
On each side of the longitudinal haemal groove, the
ventral surface of the centrum is noticeably concavely
depressed below the transverse process. This ventral haemal
groove is less sharply delimited in front than behind where
it is increased in width between the rather narrow but
elongated posterior haemal tubercles.
The distally truncated transverse processes (pl. 56,
fig. 2) are broad (minimum width, 68 mm.) and short;
they project outward and slightly downward (fig. 61a).
The neural canal is high (41 mm.) and narrow (16 mm.).
The metapophyses and most of the neural spine are de-
stroyed on one caudal (USNM 16567) and incomplete
on the other (USNM 23494).
Fourth Caudal: A decrease in the height (35 mm.) from
that of the preceding caudal but not width (20 mm.) of
the neural canal of a fourth caudal (USNM 16567) and a
less contrasting reduction in the width (15 mm.) and
height (33 mm.) of the same caudal associated with the
Ficure 61.—Views of third caudal, USNM 16567, of Dzorocetus
hiatus: a, anterior view; 5, lateral view; c, posterior epiphysis.
Abbrs.: tr., transverse process.
152
skull (USNM 23494) suggests that variation in dimensions
may not be correlated with either growth or age.
The short distally truncated transverse processes (pl.
56, fig. 3), although projected outward (fig. 62a), are
farther removed anteriorly at the base from the anterior
face of the centrum than is the posterior edge from the
posterior face.
The median ventral longitudinal haemal groove is
wider between the posterior haemal tubercles than an-
teriorly; the groove continues to be rather shallow.
The metapophyses slope less obliquely upward toward
the dorsal edge (fig. 62b) than on the preceding caudals
and do not project forward beyond the level of the anterior
face of the centrum. The neural spine has diminished in
height as well as in the anteroposterior diameter; its an-
terior edge is slanted backward.
Except for widened pedicles (61 mm.) of the neural
arch and the lesser dimensions of the neural canal, this
fourth caudal (USNM 23494) does not differ materially
from the corresponding caudal of the other series (USNM
16567).
Fifth Caudal: This caudal (USNM 16567) is differ-
entiated from the preceding caudal by the more noticeable
development of the anterior pair of haemal tubercles (pl.
56, fig. 4), the increase in the width of the median ventral
longitudinal haemal groove and reduction in the dimen-
sions of the neural canal and the neural spine.
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UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 6
The short distally rounded transverse processes are pro-
jected horizontally outward (fig. 63a). The contour of the
posterior face of the centrum of the fourth caudal is hexag-
onal. Expansion of the posterior end of the centrum is
attributable to the enlargement of the posterior pair of
haemal tubercles. On each side between the anterior and
the posterior haemal tubercle is a notch or gap through
which the segmental blood vessels pass on their upward
course on the lateral surface of the centrum in a shallow
groove which can be traced to the anterobasal angle of the
transverse process and thence to the posterior end of the
neural canal. Above each transverse process on the lateral
surface of the centrum (fig. 63b) is a longitudinal ridge
interrupted medially by the above described shallow groove
for the blood vessels. The neural canal (fig. 63a) has dimin-
ished to an ovoid passage whose width (22 mm.) is less than
its height (27 mm.). The metapophyses are lower and the
neural spine is smaller and shorter than on the preceding
caudal.
Sixth Caudal: The contour (fig. 64a) of both ends of the
centrum is definitely hexagonal, but the shape of the
posterior epiphysis is almost circular. The ends of the short
transverse processes (pl. 56, fig. 5) are obliquely truncated
from the anteroexternal angle to the posterobasal angle.
The right transverse process (USNM 16567) is pierced at
the base near the anterior edge for the passage of the
segmental blood vessels; on the left side the groove for these
Ficure 62.—Views of fourth caudal, USNM 16567, of Diorocetus hiatus: a, anterior view; }, lateral view. Abbrs.: mp., metapophysis;
tr., transverse process.
UNRECOGNIZED CALVERT CETOTHERE 153
blood vessels follows the same course as on the fifth caudal.
On the ventral surface of the centrum, the opposite haemal
tubercles are separated by the broad concave longitudinal
groove; the anterior pair of tubercles are smaller and
narrower than the posterior pair and on each side the
anterior and posterior tubercle is separated by the gap
(fig. 64b) for passage of the segmental blood vessels. A very
slight modification of the shape of the neural canal resulted
from the further reduction in the vertical diameter (22 mm.)
and the width (22 mm.); the greatest width (fig. 64a) is
more dorsal than ventral. The low metapophyses do not
project forward beyond the level of the anterior face of the
centrum. The neural spine is small and short.
In the other series (USNM 23494) the transverse processes
of the sixth caudal are broader and both are pierced at the
base for the passage of the segmental blood vessels; the
height (29 mm.) of the neural canal is greater than the
width (17 mm.) on this vertebra. The anteroposterior diam-
eter (58 mm.) of the pedicle of the neural arch of this caudal
is also greater than the same measurement (46 mm.) of the
other vertebra (USNM 16567) as described above. The
pedicles of all the caudals in this series (USNM 23494) have
a greater anteroposterior diameter than those in the other
series (USNM 16567).
Seventh Caudal: The transverse processes of the seventh
caudal (USNM 16567) are reduced to short broad flanges,
pierced centrally at the base for passage of segmental blood
vessels. Both ends of the centrum are hexagonal, but the
epiphyses are nearly circular. On the ventral surface of the
centrum the anterior pair of haemal tubercles are more
proturberant than the posterior pair; these tubercles bound
laterally the broad longitudinal haemal groove which is
strongly concave or depressed. The anterior and posterior
tubercle on each side are separated by a gap (fig. 65b) for
passage of the segmental blood vessels.
Rather broad anterior and posterior remnants of the
medially interrupted longitudinal ridge present on the
lateral face of the centrum above the transverse process
persist on this caudal. The median interruption of this ridge
is considerably wider than on the sixth caudal.
The vertical diameter (21 mm.) of the ovoidal neural
canal (fig. 65a) is not appreciably greater than its width
(19 mm.). The metapophyses are low and less spread apart
than on the preceding caudal. The neural spine is reduced
both in anteroposterior diameter and in height.
This caudal in the other series (USNM 23494) has wider
and longer transverse processes, both pierced centrally at
the base by a large foramen, a narrower (16 mm.) neural
canal but similar height (20 mm.), a narrower ventral
median longitudinal haemal groove, and a longer minimum
anteroposterior diameter (52 mm.) of pedicle of neural arch.
Eighth Caudal: Both ends of the centrum of this caudal
' (USNM 16567) are hexagonal (fig. 66a) but the posterior
epiphysis (fig. 66c) is ovoidal in contour, its vertical di-
ameter (110 mm.) exceeding the transverse diameter (105
mm.). The neural arch (fig. 66a) is low, the transverse
diameter (15 mm.) exceeding slightly the vertical diameter
(13 mm.) of the neural canal. The metapophyses are
reduced to low elongated protuberances and the neural
spine is shortened in length and height. A thick lateral
ridge pierced centrally at the base represents the reduced
transverse process. The segmental blood vessels which pass
Ficure 63.—Views of fifth caudal, USNM 16567, of Diorocetus
hiatus: a, anterior view; 6, lateral view. Abbrs.: mp., metapo-
physis; tr., transverse process.
154
through this foramen follow the groove leading therefrom
on their upward course between the anterior and posterior
vestiges of the lateral ridge (fig. 66b) to and thence through
the centrally located foramen in the pedicle of the neural
arch.
Ficure 64.—Views of sixth caudal, USNM 16567, of Diorocetus
hiatus: a, anterior view; 6, lateral view. Abbrs.; mp., metapo-
physis; tr., transverse process.
UNITED STATES NATIONAL
MUSEUM BULLETIN 247 PART 6
On the ventral face of the centrum (pl. 56, fig. 7) on each
side the anterior and the posterior haemal tubercles are
connected by an isthmus of equivalent width which forms
a bridge over the centrally located foramen for passage of
the segmental blood vessels. The longitudinal haemal
groove is broad, deeply concave, and of equal width
throughout its length.
This vertebra is not represented in the other series of
caudal vertebrae (USNM 23494).
Ninth Caudal: Both ends of the centrum (USNM 16567)
are hexagonal; the anterior epiphysis is ovoidal in outline
and the posterior epiphysis circular. The tendency for the
posterior end (fig. 67b) of the centrum to become smaller
than the anterior end apparently commences with the
ninth caudal. On each side of the ventral surface of the
centrum (pl. 56, fig. 8) the anterior haemal tubercle is
united by a broad isthmus with the posterior tubercle.
This osseous isthmus is pierced laterally at the middle of its
length by a foramen (fig. 67b) for the passage of the seg-
mental blood vessels that continue their upward course
through a vertical canal that pierces the lateral face of the
centrum for a distance of 50 to 55 mm.; these vessels
apparently reach the anterior end of the neural canal via
an obliquely directed broad groove leading from the upper
orifice of this canal. The median ventral haemal groove is
transversely widened at the middle of its length and is
deeply concave and more ovoidal than elongate. The
neural arch is low and short; the neural spine is reduced
to a low ridge. The width (16 mm.) exceeds slightly the
height (14 mm.) of the neural canal. The ninth seems to be
the most posterior caudal, which has the neural canal
roofed over by a neural arch.
This vertebra is not represented in the other series of
caudal vertebrae (USNM 23494).
Tenth Caudal: This caudal is not represented by a
centrum in one series (USNM 16567). Only the anterior
(fig. 68) and posterior epiphyses were excavated.
Near the end of the vertebral column of Recent mysticetes
the caudals are embedded in the horizontally expanded
tail ‘“‘flukes.”” These subterminal and terminal vertebrae do
not possess neural arches, transverse processes, or haemal
tubercles. This alteration occurs rather abruptly. The tenth
caudal (USNM 23494) of this Calvert cetothere is thus
modified and the ninth is the transitional caudal since it
has a reduced but complete roof for the neural arch and
longitudinal thickened ridges external to the depressed
haemal groove.
Eleventh Caudal: A smaller physically immature Calvert
cetothere (USNM 16667) has five subterminal caudals
located posterior to the hindermost caudal that has the
neural canal roofed over by the neural arch, although the
length of the roof of the neural arch of the sixth, counting
UNRECOGNIZED CALVERT CETOTHERE 155
HANS
Wy
i
ZB
SOA
SS
aes
SY
ay
Ficure 65.— Views of seventh caudal, USNM 16567, of Diorocetus hiatus: a, anterior view; 6, lateral view. Abbrs.: mp., metapophysis; tr.,
transverse process.
forward from the terminal caudal, is not more than 7 mm. The centrum of the eleventh caudal (fig. 69 a, b; USNM
There are eleven consecutive caudals in this series; the 16567) is somewhat smaller and shorter than that of the
three anterior caudals were not found. This series served ninth caudal and no remnant of the neural arch persists.
as a basis for allocating the three subterminal caudals The vertical vascular canals that pierce the centrum
(USNM 16567) hereinafter described. medially have two dorsal orifices and three ventral orifices.
Ficure 66.—Views of eighth caudal, USNM 16567, of Diorocetus hiatus: a, anterior view; 6, lateral view, reversed; c, posterior epiphysis.
156
On each side one dorsal orifice opens into the ovoidal
neural depression. The three ventral orifices (pl. 56, fig. 9)
of these vertical canals are larger than the dorsal ones; each
outer orifice is separated from the median orifice by an
interval of 27 mm. These vertical vascular canals provide
passage for the branches of the caudal artery and caudal
vein between the ventral face of the centrum and the
dorsal open neural canal or groove. The subhexagonal
anterior end of the centrum is distinctly larger than the
more circular posterior end.
Twelfth Caudal: A more noticeable foreshortening (pl.
56, fig. 10) and reduction in size of the centrum character-
izes this caudal (USNM 16567). The centrum is wider
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Ficure 68.—View of anterior epiphysis of tenth caudal, USNM
16567, of Diorocetus hiatus.
UNITED STATES NATIONAL MUSEUM BULLETIN 247 PART 6
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Airs
Tas;
Seine
C
Ficure 67.—Views of ninth caudal, USNM 16567, of Diorocetus hiatus: a, anterior view; 6, lateral view; ¢, posterior epiphysis.
(86 mm.) than high (82 mm.); its anterior end while
flattened is slightly depressed medially; the posterior end
is smaller and convex. The epiphysis was not preserved on
the posterior end (fig. 70a). Two orifices about 8 mm.
apart, for the vertical vascular canals open into a short
dorsal neural depression; the three ventral orifices open
flush with this surface.
Thirteenth Caudal: This quadrangular anteroposteriorly
compressed caudal (fig. 71b) was damaged on the left side
by the collector’s pick axe. A shallow longitudinal groove
is present on the right side about the middle of the height
of this face. The anterior end of the centrum is flattened
and the posterior end convex; the detached posterior
epiphysis was found. A transverse groove connects the two
dorsal orifices of the vertical vascular canals. The three
ventral orifices (pl. 56, fig. 11) of these vertical canals are
widely separated, the outer one 17 to 18 mm. distant from
the median orifice; all three orifices open flush with the
ventral surface of the centrum.
Ficure 69.—Views of eleventh caudal, USNM 16567, of Diorocetus
hiatus: a, anterior view; ), lateral view.
UNRECOGNIZED CALVERT CETOTHERE
One or two small terminal caudals were not preserved
in either series (USNM 16567; 23494).
Measurements (in mm.) of caudal vertebrae, USNM
23494, are as follows:
Ca.2 Ca.3 Ca.4 Ca.5 Ca.6
Anteroposterior diam- 1146> 1174 1188 103° 121
eter of centrum
Transverse diameter of 113 113 108 117 111
centrum anteriorly
Tip of neural spine to 198+ 209+ 183+ 186+ 154
ventral face of cen-
trum, posteriorly
Minimum anteroposter- 61 == 61 58 51
ior length of pedicle of
neural arch
Transverse diameter of 21 16 20 17.5 23
neural canal anteriorly
Distance between ends 260+ 247+ 232 204 170
of transverse processes
Dorsal face of meta- 162 158 156 157 170
pophysis to ventral
face of centrum (an-
terior haemapophysis)
4— Anterior epiphysis missing. P—Posterior epiphysis missing.
>—Both epiphyses missing.
Measurements (in mm.) of caudal vertebrae, USNM
16567, are as below:
CHEvRoNs.—Chevron bones are always suspended below
the intervertebral space of several anterior caudals in
skeletons of Recent mysticetes, each chevron being attached
to the pair of tubercles at the hinder end of the ventral
surface of the centrum and to the fore-end of the following
centrum.
The three anterior caudals of this Calvert cetothere
(USNM 23494; 16567) lack discernible haemal tubercles
at the fore-end of the ventral surface of the centrum. Lack
of development of these tubercles would not, however,
prevent attachment. Visible posterior haemal tubercles on
the second to ninth caudals, inclusive, indicate that at
157
least nine chevrons were present on the caudal portion of
the vertebral column anterior to the tail “flukes,” and of
these, three have been preserved of one individual (USNM
23494) and one of the other (USNM 16567).
The anterior chevron on skeletons of Recent mysticetes is
small and relatively simple, consisting of a pair of lateral
lamina which may or may not be united ventrally to form
a \V. This chevron is attached at the intervertebral space
below the first and second caudals. The second and succeed-
ing chevrons, except one or more located at the posterior
Ficure 70.—Views of twelfth caudal, USNM 16567, of Diorocetus
hiatus: a, posterior view; 6, lateral view.
end of the series possess a ventral haemal spine of varying
shape, but diminishing in vertical diameter behind the
second or third. These chevrons (pl. 57, figs. 9-11) have a
Y profile when viewed from in front, and have definitely
developed articular facets on the horizontally widened
dorsal ends of the lateral lamina.
Judging from the width of the interval separating the
opposite articular surfaces on the base of the lateral lamina,
the three largest chevrons were attached at the anterior end
of the caudal series since they articulate with the paired
posterior haemal tubercles of equivalent separation.
The largest chevron (USNM 23494) has a wide haemal
spine, the anteroposterior diameter at the extremity being
equivalent to about two thirds of its vertical diameter;
USNM 16567—Caudal Vertebrae Ca.2 Ca3 Ca4 Ca5 Ca6 Ca.7 Ca8 Cag Call Ca.l2 Ca.13
Anteroposterior diameter of centrum 136 139 137.5 120+P 114+ 8 128 GBP 2S 88 56 40
Transverse diameter of centrum, anteriorly 117 120 118 119 120 120 121 101 94 82 77
Tip of neural spine to ventral face of centrum 212+ 241 200+ 169+ 169+ 153+ 127+ 118 = = —
Minimum anteroposterior length of pedicle 50.5 54 53 49 46 47 40 26 == = =
neural arch
Transverse diameter of neural canal anteriorly 22 19 20
Distance between ends of transverse processes 257 239 et 225
Dorsal edge of metapophysis to ventral face of 176 — 169
centrum, including haemapophysis
21.5 23 19 18 16 — = =e
212 181.5 146 121 — — _— =
163 162 = — — = a As
a= Anterior epiphysis missing. »=Both epiphyses missing. »=Posterior epiphysis missing.
158 UNITED STATES NATIONAL MUSEUM BULLETIN 247
Ficure 71.—Views of thirteenth caudal, USNM 16567, of
Diorocetus hiatus: a, lateral view; b, posterior view; ¢, posterior
epiphysis.
its ventral edge (pl. 57, fig. 6) is rounded. Another large
chevron (pl. 57, fig. 7) of the same individual has the
haemal spine noticeably enlarged anteroposteriorly; its
ventral edge is nearly straight. A large chevron (fig. 72b)
of the other individual (USNM 16567) having similar
dimensions has projecting anterior and posterior basal
angles of the haemal spine and a rounded ventral edge, but
a wider separation between opposite articular facets. The
smallest chevron (USNM 23494) lacking a haemal spine
(pl. 57, fig. 8) was presumably attached to the first caudal
since the two narrow lateral lamina are united ventrally;
the interval (30 mm.) separating the opposite articular
facets is wide.
Measurements (in mm.) of the chevrons are as follows:
Posterior Anterior Anterior Anterior
USNM USNM USNM USNM
23494 23494 23494 16567
Vertical diameter of 54 81 7 71
chevron
Greatest anteroposterior = 52.5 62 58
diameter of haemal spine
at extremity
Anteroposterior diameter 23 47 47 41.5
of articular facet on base
of right lateral lamina
Least distance between in- 30 2255) 22 32
ternal margins of oppo-
site articular facets
Forelimb
Right and left scapulae, the proximal detached end of
the right humerus, right and left ulnae, seven carpals, five
metacarpals, and two phalanges were associated with one
of the skulls (USNM 23494).
Assuming that the length of the complete humerus was
not less than 180 mm. and not greater than 220 mm. the
upper portion of the forelimb of this physically immature
PART 6
Ficure 72.—Views of anterior chevron, USNM 16567, of Diorocetus
hiatus: a, anterior view; ), lateral view.
cetothere comprising the scapula, humerus, radius, and
adjacent ulna measured at least 27 inches (685 mm.) and
not more than 28% inches (725 mm.) in length. Too few
of the terminal bones, carpals, metacarpals, and phalanges
were found to provide a basis for estimating the length of
the entire forelimb. A normal flattened mysticete flipper
or paddle is indicated, however, by the shape of the indi-
vidual bones.
ScapuLa.—As compared with the scapula of Recent
mysticetes available for comparison, that of this Calvert
cetothere is distinguished by greater height in proportion
to its length, the vertical diameter being equivalent to about
seven tenths of the latter, and by the more regular curvature
of the vertebral margin.
The left scapula lacks the anterovertebral angle, the
coracoid, the posterior half of the articular head and a 60
mm. section of the adjoining posterior border of the blade.
The anterovertebral and posterovertebral angles of the
blade of the right scapula (pl. 52, fig. 1) are missing and
the extremity of the coracoid is eroded. The acromion on
both scapulae is damaged.
Above the articular head, the external and internal
surfaces of the blade are abruptly depressed. A concave
curvature characterizes the anterior and posterior margins
of the blade. The blade, particularly the posterior border,
is thickened toward the articular head, the upper two
thirds being rather thin. The prescapular border of the
blade is very narrow internal to the acromion, but widens
toward the anterovertebral angle, and is deflected obliquely
inward. The spine of the scapula is represented by a ridge
that extends upward from the acromion almost to the
vertebral margin, and the acromion is a relatively broad
flattened process that gradually curves inward toward its
extremity. The glenoid cavity is concave, the ratio of its
exterointernal diameter to its anteroposterior diameter
being 7 to 10. The attenuated and laterally flattened
coracoid projects forward and inward slightly above the
glenoid border.
UNRECOGNIZED CALVERT CETOTHERE
Micaxreneracrs (in mm.) of the scapula of USNM 23494
are as follows:
Right Left
Greatest anteroposterior diameter of scapula, 345-+ 345-+>
estimated
Greatest anteroposterior diameter of scapula, as 290 335
preserved
Greatest vertical diameter, articular head to 234 230
vertebral margin
Length of coracoid, superior margin at base to 33+> =
distal end
Posterior face of articular head to distal end of 115+ —
coracoid
Length of acromion, superior margin at base to 65+ 75+
distal end
Greatest anteroposterior diameter of articular 85 =
head
Greatest transverse diameter of articular head 58 58
Humerus.—The detached proximal end of the right
humerus (USNM 23494) does not with any degree of
certainty provide a basis for estimating the length of this
bone either at the time of death or when physically mature.
One Calvert humerus measuring 180 mm. in length and a
larger one 220 mm. in length have a head of approximately
the same dimensions; the proximal ends of both of these
humeri are firmly ankylosed to the shaft.
The anteroposterior diameter of the convex head is
greater than the transverse. The head is set off from the
radial tuberosity by a groove which expands on the internal
side into a broad smooth surface. The projecting radial
tuberosity is eroded.
Raprus.—Neither the right nor the left radius was found
when this skeleton (USNM 23494) was excavated. A right
radius (USNM 23019; fig. 73) from zone 11 of the Calvert
formation, 1% miles south of the former Plum Point wharf,
Md., corresponds in length to the ulna (USNM 23494),
but represents a physically mature individual. This ulna
measures 275 mm. in length; the greatest anteroposterior
diameter of the proximal end is 62 mm. and the greatest
transverse diameter is 41 mm. The anterior profile of the
shaft curves forward proximally, but is nearly straight on
the distal two thirds; the external face is convex and the
internal flattened. The proximal facet, which articulated
with the radial facet of the humerus, is shallowly concave
and the facet on the posterior face of the proximal end for
articulation with the ulna is relatively small, its transverse
diameter being 31 mm. and the proximodistal diameter
15 mm. The anterior edge of the shaft is more rounded than
the posterior edge.
Uina.—The left ulna (USNM 23494) is complete and the
_ right one lacks the dorsal portion of the olecranon process;
159
both have the relatively slender and transversely compressed
shaft curved from end to end. The greatest length of the left
ulna (pl. 53, fig. 4) is 289 mm. and the distance from the
upper margin of the radial facet (radial margin of greater
sigmoid cavity) to the distal end of the shaft is 240 mm.
The distal or carpal end of the shaft of this left ulna measures
64 mm. anteroposteriorly and 24 mm. transversely; this
end is roughened for the attachment of the incompletely
Ficure 73.—Internal view of
right radius, USNM 23019,
of (?) Diorocetus hiatus.
ossified epiphysis. The greater sigmoid cavity is pitted,
indicating a cartilaginous covering layer and the same
condition exists on the posterior curved face of the olec-
ranon. The width of the greater sigmoid cavity decreases
toward the dorsal attenuated end of the olecranon; the
transverse width of the greater sigmoid cavity below and
near its radial margin (36 mm.) is nearly twice the greatest
width (22 mm.) of the olecranon posteriorly. The proximal
facet for articulation with the radius is weakly developed.
160
The minimum anteroposterior diameter of the shaft is
44 mm. and the minimum transverse diameter 16 mm.
near the distal end. The anterior and posterior edges of
the shaft are rounded, except for the slightly developed
ridge-like crest anteriorly on the dorsal half of the shaft.
CarpaLs.—The seven carpal bones are not sufficiently
ossified to indicate their later growth shapes and thus
permit allocation to their normal position in the carpus.
Two of them possess one smoothly flattened surface, but
elsewhere they are porous and immature; four carpals
are roughened for attachment of cartilaginous tissue.
METACARPALS AND PHALANGES.—The thickness of the
shaft suggests that five of the forelimb bones (USNM
23494) are metacarpals. The longest finger bone (pl. 57,
fig. 2) measures 46 mm. in length and the shortest (pl. 57,
fig. 3) 40 mm.; the transverse diameter exceeds the dorso-
plantar diameter of the shaft and all are constricted to a
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 6
varying degree near the middle of their length. One end
of each finger bone is enlarged more than the other, and
both ends are pitted for attachment of cartilaginous tissue.
The two smallest bones (pl. 57, figs. 4, 5) presumably are
phalanges, since the shafts are distinctly flattened in a
flexor-extensor direction. These bones measure 37 mm. and
36 mm., respectively, in length; they are constricted medi-
ally, the minimum transverse diameter of the longest being
15 mm. Both ends of each of these bones are roughened
for attachment of cartilaginous tissue. Dissection has
shown that the number of phalanges comprising each of
the four finger bones inclosed in the right and left fore-
flipper of two individuals of the little piked whale (Bala-
enoptera acutorostrata), counting across from the radial
(front) edge, was 3-8-6-3 on one and 4-7-6-3 on the
other, a total of twenty. A similar arrangement of the bones
in the manus of this Calvert cetothere would have added
at least 11¥%-inches (288 mm.) to the foreflipper length.
BIBLIOGRAPHY
ABEL, OTHENIO
1938. Vorlaeufige Mitteilugen ueber die Revision der fossilen Mystacoceten aus dem Tertiaer.
Belgiens. Bull. Mus. roy. d’Hist. nat. Belgique, Bruxelles, vol. 14, no. 1, pp. 1-34,
6 figs. February 1938.
BRANDT, JOHANN FRIEDRICH
1843a. De Cetotherio, novo Balaenarum familiae genere in Rossia meridionali ante aliquot
annos effosso. Bull. cl. phys.-math. Acad. Imp. Sci. St. Pétersbourg, vol. 1, nos.
10-12, pp. 145-148. February 2, 1843.
1843b. Rapport sur les travaux de Académie pendant l’année 1842: Zoologie et Physiologie.
L’Institut Journ. Sci. Math. Phys. et Nat., Paris, vol. 11, no. 499, p. 241. July 20,
1843.
1843c. Supplément au rapport sur les travaux de l’Académie pendant l’année 1842. Paléonto-
logie. L’Institut Journ. Sci. Math. Phys. et Nat., Paris, vol. 11, no. 502, p. 270.
August 10, 1843.
CAPELLINI, GIOVANNI
1876. Sulle Balene Toscane. Nota. Atti R. Accad. Lincei, Roma, ser. 2, vol. 3, pt. 2, pp. 9-14.
1877. Balenottere fossili e Pachyacanthus dell’Italia meridionale. Atti R. Accad. Lincei, Mem.
Cl. sci. fis., Roma (3), vol. 1, pp. 611-530, 3 pls.
1905. Balene fossili Toscane, III: Idiocetus guicciardinii. Mem. Roy. Accad. Sci. Bologna
ser. 6, vol. 2, pp. 71-80, 2 pls.
KELLocc, REMINGTON
1965. Fossil marine mammals from the Miocene Calvert formation of Maryland and Virginia,
1: A new whalebone whale from the Miocene Calvert formation. U.S. Nat. Mus.
Bull. 247, pt. 1, pp. 1-45, figs. 1-28, pls. 1-21. October 15, 1965.
ScHULTE, HERMANN VON WECHLINGER
1916. Monographs of the Pacific Cetacea, II: The sei whale (Balaénoptera borealis Lesson).
2: Anatomy of a foetus of Balaénoptera borealis. Mem. American Mus. Nat. Hist.,
new series, vol. 1, pt. 6, pp. 391-491, 10 figs., pls. 43-57. March 1916.
UNRECOGNIZED CALVERT CETOTHERE 161
TRUE, FREDERICK WILLIAM
1907. Remarks on the type of the fossil cetacean Agorophius pygmaeus (Miller). Publ. 1964
Smithson. Inst. Washington, 8 pp., pl. 6.
TurRNER, WILLIAM
1892. The lesser rorqual (Balaénoptera rostrata) in the Scottish seas, with observations on its
anatomy. Proc. Roy. Soc. Edinburgh, 1891-1892, pp. 36-75, 4 figs.
Van BENEDEN, PIERRE JOSEPH
1836. Observations sur les caractéres spécifiques des grandes cétacés, tires de la conformation
de Poreille osseuse. Ann. Sci. Nat., Paris, ser. 2, vol. 6, Zoologie, pp. 158-159.
1880. Les Mysticétes 4 courts fanons des sables des environs d’Anvers. Bull. Acad. roy. Sci.
Lettres et Beaux-Arts, Belgique, Bruxelles, ser. 2, vol. 50, no. 7, pp. 11-27.
1886. Description des ossements fossiles des environs d’Anvers, Part 5: Cétacés. Genres:
Amphicetus, Heterocetus, Mesocetus, Idiocetus and Isocetus. Ann. Mus. roy. d’Hist. nat.
Belgique, Bruxelles, ser. Paléontologique, vol. 13, pp. 139, pls. 75.
WALMSLEY, ROBERT
1938. Some observations on the vascular system of a female fetal finback. Contr. Embryol.,
Carnegie Inst. Washington, Publ. 496, no. 164, pp. 107-178, 27 figs., 5 pls. May
31, 1938.
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7. A Sharp-nosed Cetothere From the Miocene Calvert
NADEQUACY OF RECOVERED SKELETAL REMAINS of many
described fossil mysticetes hampers comparable evalua-
tion of attributed generic criteria. Continued uncertainty
regarding the significance of observable differences in the
telescoping or the slippage forward or backward of the
cranial and rostral bones of the mysticete skull may persist
until a larger number of representative types of mysticetes
from successive geological faunas are recorded. It must be
acknowledged that some skepticism is warranted regarding
the validity of mysticete generic diagnoses based in whole
or in part on such criteria as the conformation of the
articular condyle of the mandible, the position of internal
gingival (nutrient) and external mental foramina, the
dimensions of the mandibles, unless comparable growth
stages can be established, or the size of the tympanic bulla.
Notwithstanding such considerations it seems desirable
to allocate a recognizably different specimen to a genus
currently accepted as valid. The specimen hereinafter
described is considered to be a smaller but geologically
more recent member of the genus Aglaocetus. Lydekker in
1894 seems to have been the first to direct attention to the
occurrence of the skull and associated vertebrae of a whale-
bone whale in a bed of mixed sand and clay belonging to
the Patagonian (lower Miocene) marine formation at
“el cerro del Castillo,” opposite Trelew, province of
Chubut, Argentina. A second skull from the same locality
and a third skull (Kellogg, 1934), excavated on a small
hill southwest of Pico Salamanca in the same province,
have further elucidated the relations of the bones of the
skull of this Patagonian Aglaocetus moreni.
AGLAOCETUS Kellogg
Aglaocetus Kellogg, 1934, Contrib. Palaeont., Carnegie Inst.
Washington, publ. 447, p.65. January 10, 1934.
Type species: Cetothertum moreni Lydekker.
275-699—68 3}
AGLAGCETUS PATULUS, new species
Type specimen: USNM 23690. Skull (essentially com-
plete, except for both lachrymals and jugals, and pterygoids
in region of the pterygoid fossae), both tympanic bullae,
left periotic, atlas, two cervical vertebrae, two dorsals,
eight lumbars, and rib fragments. Collectors, Robert E.
Weems, Frank C. Whitmore, Jr., and Albert C. Myrick,
Jr.; April 6, 1966.
Horizon and Locality: About 3.5 feet above base of bluff
in blue marly clay of zone 14, approximately 3.7 miles
below mouth of Pope’s Creek in Stratford Bluffs, about
1200 feet beyond swamp below (east of) “Big Meadows,”
Westmoreland Co., Va., Calvert formation, middle
Miocene.
Referred Specimen: Two as follows: (1) USNM 13472;
posterior portion of basicranium, apex of supraoccipital
shield, right and left supraorbital processes of frontals,
interorbital region of frontals, portions of maxillary and
premaxillary, vomer, right and left periotics, right tym-
panic bulla, coll. Raymond M. Gilmore, C. Lewis Gazin
and Remington Kellogg, August 9-10, 1933; in zone 14,
Kenwood Beach cliff, about 428 yards south of road end
at Governor Run, Calvert Co., Md., Calvert formation,
middle Miocene. (2) USNM 23049; right squamosal
incomplete, right periotic, ten lumbars, nine caudals, five
chevrons, right scapula fragments, two metatarsals, two
phalanges, rib fragments, coll. Wallace L. Ashby, jr.,
Frank C. Whitmore, jr., John E. Ott, Leroy Glenn, jr.,
and Remington Kellogg, July 15, 1963; base of zone 14,
about 18 feet above beach level, 180 feet south of north
end of first cliff south of mouth of Parker Creek, Cal-
vert County, Md., Calvert formation, middle Miocene.
Diagnosis: Resembling Aglaocetus moreni (Kellogg, 1934,
p- 66) in having the posteroexternal angle of the maxillary
enlarged, its broad ventral plate underlapping the supra-
orbital process of the frontal. Resembling A. moreni and
163
164 UNITED STATES NATIONAL MUSEUM BULLETIN 247
**Tdiocetus’ laxatus (Van Beneden, 1886, pl. 54) in the
limited interdigitation of rostral and cranial elements as
well as in the shape of the triangular occipital shield.
Differing from the Patagonian lower Miocene species in the
following features: rostrum wider, less attenuated and
lateral profile more convex; ascending process of maxillary
shorter, less extended backward; apex of triangular occipital
shield carried farther forward to level of center of orbit;
zygomatic process of squamosal more robust, directed
more forward and less obliquely outward. Presence of large
foramen near anterior end of nasal may have no especial
significance. From the Belgian upper Miocene (Anversian)
genus, this mysticete differs in having the interdigitation of
median rostral elements with cranium on_interorbital
region less accentuated; apex of triangular occipital shield
carried forward to level of center of orbit; shorter inter-
temporal constriction; and zygomatic process of squamosal
more robust.
The following combination of characters serve also to
characterize this mysticete: slender nasals located for most
part anterior to preorbital angles of the supraorbital
processes; limited backward overriding of median inter-
orbital region carrying rostral elements (ascending processes
of maxillaries and premaxillaries and the nasals) barely
beyond the level of preorbital angles of supraorbital
processes of frontals; rostrum broad at base, each maxillary
having an enlarged posteroexternal angle and a broad
ventral plate underlapping the supraorbital process of
the frontal; a short intertemporal constriction formed by
opposite parietals; exposure of frontals in interorbital
region reduced to a narrow strip; lateral protuberance of
basioccipital large, elongated; anteroposteriorly compressed
extremity of postglenoid process thin. Dome of pars cochlearis
of periotic neither enlarged nor prolonged ventrally;
posterior process narrow, with deep longitudinal groove
for facial nerve; labyrinthic region bulbous. Neural canal
of posterior cervical vertebrae unusually low and wide;
pedicles of neural arch short and much wider transversely
than anteroposteriorly; neural spine short and thin; atlas
lacks hyapophysial process.
Skull
DorsaL view.—Interlocking of the rostral and cranial
portions of the skull (pls. 58-59) is effected in part by the
splitting of the posterior extremity of each maxillary into
a dorsal ascending process and a ventral plate. Behind the
nasal fossa the relatively narrow internal ascending process
of the maxillary is held in position in the rather deep sutural
grooves on the upper surface of the interorbital portion of
the corresponding frontal. Most of the dorsal surface of
the relatively wide supraorbital process of the frontal is
bare and not overridden by the hinder end of the maxillary.
PART 7
SOF Pre
Pa.
ZE-
Ss Sq.
——
Aes CYVYD an
Ex.06.
Ficure 74.—Dorsal view of skull, USNM 23690, of Aglaocetus
patulus. Abbrs.: ant.n., antorbital notch; Bo., basioccipital; c.,
occipital condyle; Ex. oc., exoccipital; f.m., foramen magnum;
fmax., maxillary foramen or incisure; f.ov., foramen ovale;
Fr., frontal; h.pt., hamular process of pterygoid; j.n., jugular
notch or incisure; l.pr., lateral or descending protuberance of ©
basioccipital; Max., maxilla; m.e.a., channel for external |
auditory meatus; Na., nasal; 0.c., optic canal; Pa., parietal; —
Pal., palatine; pgl., postglenoid process; Pmx., premaxilla; |
pr.a., anterior process of periotic; pr.p., posterior process of _
SHARP-NOSED CETOTHERE 165
The broad ventral plate of the maxillary is extended back-
ward beneath the anterior border of the ventral surface of
the supraorbital process of the frontal almost to the optic
channel.
At the base of the rostrum (fig. 74) the maxillaries are
quite broad, attributable in part to the posteroexternal
enlargement. In this respect this portion of the skull approxi-
mates the similarly widened posterior end of the maxillary
of the lower Miocene Patagonian Aglaocetus moreni (Kellogg,
1934, fig. 2). The angle formed by the thin outer edge
with this posteroexternal enlargement constitutes the antor-
bital notch of the maxillary, From the level of the longi-
tudinal premaxillary maxillary contact the dorsal surface
of each maxillary slopes downward to its outer margin.
Along its internal border each maxillary is overlain by the
corresponding premaxillary. At least the internal face of
the hinder half of each maxillary abuts against the outer
surface of the troughlike vomer. On this skull the backward
overslippage above the narrow interorbital portion of the
frontals by the median portion of the rostrum has carried
the hinder ends of the ascending processes of the premaxil-
laries and maxillaries as well as the nasals behind the level
of the preorbital angle of the supraorbital process of the
frontal but not to the center of the orbit, the dorsal ascend-
ing process of each maxillary being short and rather narrow.
Behind the level of the anterior ends of the nasals, three or
four foramina are present in each maxillary external to the
premaxillary maxillary contact. At least twelve foramina
are present in the right maxillary. The largest of these
foramina on the right side is 50 mm. behind the anterior
end of the nasal. There are four small foramina in an
interval of 50 to 75 mm. in front of the right nasal. About
65 mm. internal to the outer margin and 110 mm. anterior to
the antorbital notch two small foramina are present.
These foramina are not located in the area corresponding
to the oblique incisure on the skull of USNM 16783.
In front of the nasal fossa, each premaxillary is noticeably
flattened and projects forward beyond the maxillary, Each
premaxillary attains its greatest width (77 mm.) at the
level of the anterior ends of the maxillaries. The dorsoin-
ternal edges of the opposite premaxillaries parallel one
another from the extremity of the rostrum to the anterior
end of the nasal fossa. Prior to the distortion resulting from
crushing, each premaxillary rested in the groove on the
dorsointernal edge of the corresponding maxillary along
the dorsal nasal fossa. Each narrowed premaxillary is
bent downward and is also curved outward and then in-
ward to conform to the curvature of this fossa. The rather
periotic; Pt., pterygoid; pt.f., pterygoid fossa; S.oc., supra-
occipital; Sq., squamosal; s.or.pr., supraorbital process of
frontal; Ty., tympanic bulla; Vo., vomer; zyg., zygomatic
process.
narrow ascending process of each premaxillary is lodged
in two or three sutural grooves on the dorsal interorbital
surface of the frontal. The troughlike vomer forms the
floor of the elongated nasal fossa.
The relatively long (235 mm.) nasal bones taper from
their anterior to their posterior ends and are wedged in
between the ascending processes of the opposite premaxil-
laries. Their posterior ends are lodged in sutural grooves
on the interorbital surface of the frontal and anteriorly
they overhang the nasal fossa. For most of their length the
nasals are projected forward above the nasal passages
beyond the level of the preorbital angle of the supraorbital
process of the frontal. They do not extend backward beyond
the level of the posterior ends of the ascending processes
of the premaxillaries and maxillaries. The anteroexternal
angle projects forward beyond the anterointernal angle of
the right nasal, forming a concavely curved anterior edge.
A hole or foramen is present behind the anterior edge of
each nasal (fig. 74), possibly the result of fortuitous damage.
The frontals are narrowly exposed in the median inter-
orbital region and are excluded from the vertex by the
parietals. Between the hinder ends of the median rostral
elements and the intertemporal constriction contributed
by the parietals, the frontals are exposed for about 10 mm.
Each supraorbital process of the frontal slopes gradually
from the median interorbital region to its orbital rim. No
curved transverse temporal crest seems to have been
present, although such a crest, if developed, may have
been obliterated by crushing. A rounded preorbital angle,
a thick postorbital projection, and a thin arched orbital
rim characterize the supraorbital process of the frontal.
The rostral wall of the cranium is contributed largely by
the frontals. Posteriorly, the frontal is overspread by the
thin anterior border of the corresponding parietal. The
lachrymals and the jugals were not preserved with this
skull.
The parietals, which meet medially to constitute the
short (50 mm.) intertemporal ridge, are each overridden
above and behind by the external border of the large tri-
angular supraoccipital shield. Anteriorly, the thin anterior
border of the parietal overspreads the frontal and the base
of its supraorbital process and extends forward almost to
the level of the posterior margin of the ascending process
of the corresponding maxillary. The nearly vertical parietal
constitutes a major portion of the lateral wall of the
braincase.
The posterolateral portion of the cranium is constituted
by the large thick squamosal. From its anterior sutural
contact with the pterygoid, the squamosal curves back-
ward, outward and forward to the extremity of its zygo-
matic process around the temporal fossa. The zygomatic
process is stout and is directed obliquely forward. Erosion of
the dorsal surface of both zygomatic processes prevents
166 UNITED STATES NATIONAL MUSEUM BULLETIN 247
determination of the existence of a lengthwise continuation
of the lambdoid crest.
A strong forward thrust of the supraoccipital shield has
carried its acutely pointed apex to the level of the center
of the orbit. At the level of the foramen magnum the trans-
verse diameter (360 mm.) of the supraoccipital exceeds the
greatest distance (305 mm.) from the dorsal rim of the
foramen magnum to the apex. Most of this dorsally atten-
uated shield is depressed medially below the level of its
lateral margins.
The exoccipitals are, with the exception of their outer
ends, concealed from a dorsal view by the posterior over-
hang of the lambdoid crest. The large flattened occipital
condyles do not project backward beyond the level of the
extremities of the exoccipitals.
Ficure 75.—Posterior view of skull, USNM 23690, of Agdaocetus
patulus. For abbreviations, see figure 74.
PosTERIOR viEW.—The dorsally attenuated triangular
occipital shield (fig. 75), which constitutes essentially
the entire posterior wall of the braincase, consists of the
medially depressed supraoccipital and on each side of the
foramen magnum the exoccipital. On each side the lamb-
doid crest on the posterior edge of the squamosal above the
exoccipital curves upward and then forward along the
external edge of the supraoccipital to its acutely pointed
apex. No median vertical ridge is developed on this bone
above the foramen magnum. Each exoccipital comprises
a lateral wing of the posterior triangular shield.
From a posterior view it is seen that the foramen magnum
is relatively large and ovoidal in outline. The large occipital
condyles are less convex from side to side than from end to
end. They are separated ventrally by a deep wide notch.
On each side of the median basicranial depression is the
large downward projected lateral protuberance of the
basioccipital. The external face of this protuberance
constitutes the inner limit of the large notch or incisure for
the jugular leash. External to the exoccipital the distally
rounded postglenoid process extends downward 98 mm.
below the level of the ventral edge of the occipital condyle
and 70 to 82 mm. below the level of the ventral edge of
the adjacent exoccipital. Except in the details just noted
and in certain differences in the profiles of individual
PART 7
bones, the relations of the component parts of the hinder
end of the cranium are similar to USNM 23494.
LATERAL ViEw.—The apex of the supraoccipital shield,
the highest point of the dorsal profile, rises very little above
the lateral margins of this shield, but more abruptly above
the short intertemporal ridge. The slope from the median
interorbital region to the extremity of the rostrum is very
gradual. The greatest depth of the rostrum is at the anterior
end of the palatines. The outer edge of the maxillary is
thin throughout its length anterior to the antorbital notch.
The arched orbital rim of the supraorbital process of the
frontal is dorsoventrally compressed, the preorbital angle
is somewhat thinner than the underlying ventral plate of
the maxillary and the postorbital angle is noticeably thick-
ened dorsoventrally. The downward slope of the supra-
orbital process of the frontal from the median intertemporal
region to the orbital rim is gradual.
The dorsoventral diameter of the basal portion of the
postglenoid process (80 mm.) is almost twice the same
measurement of the anterior end of the zygomatic process
(44 mm.). Viewed from the side the posterior surface of the
postglenoid process slopes obliquely downward and back-
ward.
The nearly vertical parietal is concavely curved from end
to end and contributes a major portion of the lateral wall of
the braincase, meeting its opposite dorsally to form a short
intertemporal ridge and overspreading the base of the
frontal. The small alisphenoid is visible in the lateral wall
of the braincase behind the base of the supraorbital process
of the frontal above the pterygoid and below the parietal.
The occipital condyles are not visible when the skull is
viewed from the side.
VENTRAL vieEw.—Except for the immediate region of the
pterygoid fossa and portions of the ventral surface of the
maxillaries, this skull (USNM 23690; pl. 59) is exceptionally
complete. The major portion of the ventral surface of the
rostrum is contributed by the maxillaries, which prior to
deformation as the result of being shoved over the centra of
dorsal vertebrae, met longitudinally along the midline of
the rostrum, concealing the keel of the vomer. The presence
of an unusually large posteroexternal angle on each maxil-
lary has accentuated the narrowing of the rostrum. Flatten-
ing of the ventral surface of the maxillary is most obvious
external to the median downward convex curvature, which
conforms to the shape of the vomer against which it abuts.
Along the anterior border, the supraorbital process of the
frontal is underlapped by the thin posterior end of the
corresponding maxillary. The ventral surface of each
maxillary (fig. 76) is engraved by a series of grooves which,
unfortunately as a result of poor preservation of the original
surface in certain areas, cannot be traced in their entirety.
The grooves near the posterior end of each maxillary
opposite and in front of the palatine are quite short and
SHARP-NOSED CETOTHERE
are directed obliquely outward and backward. These
grooves serve as channels for the nutrient vascular vessels
and nerves that supply the palate and attached baleen of
the living mysticetes. Except for a relatively few short ones
more anteriorly along the outer border, the majority of
Ls
Pal.
Ficure 76.—Ventral view of skull, USNM 23690, of Aglaocetus
patulus. For abbreviations, see figure 74.
167
the anterior grooves run lengthwise or nearly so. The right
maxillary terminates 1370 mm. anterior to the posterior
margin of the vomer and the right premaxillary extends
95 mm. beyond the maxillary. The distance from the
anterior end of the right maxillary to the anterior edge of
the optic channel at the base of the right supraorbital
process is 1230 mm. The inner edges of the opposite maxil-
laries commence to diverge slightly on the ventral surface
of the rostrum 115 mm. behind the anterior end of the
right maxillary.
At a point 130 mm. in advance of the posterior end of its
horizontal plate the ventral keel of the vomer develops a
narrow flattened surface, which is extended backward at
the same horizontal level for 75 mm., and then, as a con-
tinuing thin vertical partition between the choanae,
diminishes in vertical diameter until it disappears about
at the posterior end of the vomer. The horizontal plate of
the posterior end of the vomer conceals the basisphenoid
from a ventral view and laterally is in contact with the
corresponding edge of the vaginal process of the pterygoid.
Although the posterior border of each palatine is broken
off and the precise termination of the anterior end uncertain
on account of sloughing off of the thin borders of this bone,
the anteroposterior diameter of each palatine was at least
300 mm. Each palatine anteriorly and externally over-
spreads the ventral surface of the corresponding maxillary.
Posteriorly each palatine is suturally united with the
pterygoid which contributes the missing internally project-
ing hamular process. The lachrymal and jugal bones were
not attached to this skull and presumably were disassociated
prior to burial by sediments.
The distally expanded supraorbital processes of the
frontals are extended outward to the level of the large
posteroexternal angles of the maxillaries. The deep channel
for the optic nerve commences at the optic foramen and
curves outward on the ventral surface of the supraorbital
process of the frontal and, increasing in width, becomes
very wide near the orbital rim of this process.
On the internal two thirds of its length this optic channel
resembles a partly closed tube, being bordered posteriorly
by a thin osseous wall up to 35 mm. in vertical diameter,
which terminates about 100 mm. from the external orbital
rim. This deep posterior wall of the optic channel, the proxi-
mal portion of which is certainly complete on both supra-
orbital processes, seems to be contributed by the frontal,
since no sutural contact with either the alisphenoid or
parietal could be detected. The anterior wall of this optic
channel (vertical diameter near its origin as much as 30
mm.) is contributed by the dorsoventral thickening of the
supraorbital process. In width on the left process, this
channel increases from a minimum of 20 mm. near its
origin to a maximum of 50 mm. at the point where the
posterior wall vanishes on the rim. The relationship of the
168
orbitosphenoid cannot be determined since its normal
position within this partly closed optic channel is hidden
from view.
The central exposure of the basioccipital between its
large lateral descending protuberances (left, transverse
diameter, 55 mm.) is rectangular; its line of contact with
the basisphenoid is overspread by the horizontal plate of
the vomer. The flattened external surface of the lateral
protuberance slopes obliquely upward. Anteriorly each
lateral descending process or protuberance is overspread
by the hinder end of the corresponding vaginal plate of
the pterygoid, which is also in contact along its dorsoin-
ternal edge with the horizontally widened plate of the
posterior end of the vomer. This portion of the pterygoid
also contributes the inner outer wall of the corresponding
internal choana. Only the broken off basal portion of the
right hamular process is preserved on tnis skull. The
attenuated anterior portion of the pterygoid is extended
forward beyond the level of the internal end (origin) of
the optic channel and is also suturally united along its
internal edge with the palatine. The main portion of the
pterygoid is suturally united in front with the hinder end
of the palatine and behind with the bifurcated end of the
squamosal which encloses the foramen ovale. The greatest
anteroposterior diameter of the left foramen ovale is 26
mm. and the greatest transverse diameter 15 mm. The
pterygoid comes in contact with the lower surface of the
alisphenoid on the inner wall of the temporal fossa and is
also narrowly in contact with the parietal.
The small pterygoid fossa is bounded internally by the
vaginal process of the pterygoid, anteroexternally by the
downward curving thickened anterior and external borders
of the pterygoid, and to a limited extent by the falciform
process of the squamosal. The roof of this air-containing
fossa and the floor also to some extent is formed by the
pterygoid; it is continuous posteriorly with the tympano-
periotic recess. The extent to which the pterygoid con-
tributes the floor of this fossa cannot be readily determined,
since no remnants other than broken edges of this bone are
present. The reconstruction of the pterygoid in the region
of the pterygoid fossa shown on figure 76 is therefore some-
what conjectural.
The squamosal and its falciform process externally, the
pterygoid anteriorly, the lateral protuberance of the
basioccipital internally, and the exoccipital posteriorly
enclose the tympanoperiotic recess. A broad notch or
incisure on the exoccipital between the lateral protuberance
and the pars cochlearis of the periotic corresponds to the
posterior lacerated foramen for the jugular leash.
On the ventral surface the contact between the squa-
mosal and the exoccipital is concealed by the posterior
process of the periotic which is securely lodged in a deep
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 7
groove. Between the posterior process of the periotic and
the base of the hinder face of the postglenoid process is
the rather broad (15 mm.) and shallow groove for the
external auditory meatus.
The elongated zygomatic process is directed more forward
than outward and is in direct contact with the postorbital
projection of the supraorbital process of the frontal. Each
postglenoid process is deflected obliquely backward and
has its thin anteroposteriorly compressed extremity extended
55 mm. below the level of the lateral protuberance of the
basioccipital. The posterior face of each postglenoid process
is deeply concave and the anterior face is convex. The
glenoid articular surface is concavely curved from extremity
of postglenoid process to tip of zygomatic process (length,
left process, 273 mm.). External to the excavation for the
pro-otic portion of the periotic and in front of the sharp
edged posterior rim, a relatively shallow concavity is present
on the ventral surface of the squamosal.
The outer ends of the exoccipitals project backward
slightly (12 mm.) beyond the level of the posterior articular
surfaces of the occipital condyles. Although no definite
paroccipital processes are developed for the attachment of
each stylohyal, a small cavity is present on the corresponding
area on the left exoccipital. The occipital condyles are not
protuberant and are separated by a deep narrow (15 mm.)
groove.
Measurements (in mm.) of the skull, USNM 23690, are
as follows:
Greatest length of skull, anterior end of right pre- 1635
maxillary to level of posteroexternal angle of right
exoccipital
Distance from anterior end of right premaxiliary to 1600
posterior articular face of right occipital condyle
Distance from anterior end of right premaxillary to 1253
apex of supraoccipital shield
Greatest length of right premaxillary 1167
Distance from apex of supraoccipital shield to posterior 68
end of right nasal bone
Transverse diameter of skull across posteroexternal 775
angles of supraorbital processes of frontals
Transverse diameter of skull across preorbital angles of 770
supraorbital processes of frontals
Greatest anteroposterior diameter of extremity of left 205
supraorbital process of frontal
Transverse diameter of skull across outer surfaces of 760
zygomatic processes
Transverse diameter of skull between outer edges of ex- 490
occipitals
Transverse diameter between outer edges of occipital 167
condyles
Greatest or obliquovertical diameter of right occipital 85
condyle
Greatest transverse diameter of right occipital condyle 69
SHARP-NOSED CETOTHERE 169
Greatest transverse diameter of foramen magnum 46
Distance from dorsal rim of foramen magnum to apex 305
of supraoccipital shield
Distance between anterior end of right premaxillary and 1615
extremity of right postglenoid process
Distance between anterior end of right premaxillary and 1230
edge of optic channel (groove) at origin
Right nasal, length externally 235
Right nasal, length internally 230
Right nasal, width anteriorly 50
Right nasal, width at base 15
Greatest breadth of basioccipital across lateral pro- 180+
tuberances, outside measurement
Greatest length of left zygomatic process, extremity of 273
postglenoid process to anterior end
Distance from posterior surface of right occipital condyle 132
to posterior end of vomer
Distance from posterior surface of right occipital condyle 520+
to anterior edge of right palatine
Posterior edge of vomer to anterior edge of right palatine 390+
Distance between opposite foramina ovale 292
Tympanic Bulla
The left tympanic bulla (USNM 23690) was crushed
against the left periotic on the type skull. The right bulla
(USNM 13472) was pushed partially into the tympan-
operiotic recess on the referred skull.
The type bulla (pl. 60, figs. 3-5) differs from the referred
bulla (USNM 13472) in having the posterior end pinched
in medially and attenuated ventrally to form a broad
V-shaped vertical depression, an acute projecting ventro-
internal angle, a less abruptly backward bending extremity
of the sigmoid process, and a broader vertical groove in
front of the sigmoid process. On the ventral face of the
type bulla a low crest, which is better developed near the
ends than at the middle, extends obliquely from the
posteroexternal to the anterointernal angle. No trace of
his crest is visible on the referred bulla.
The posterior pedicle arises internally from the posterior
end of the involucrum and externally, behind the low
blunt conical apophysis, from the posterior end of the thin
curved outer lip.
The involucrum is creased transversely near the middle
of its length; the eustachian outlet of the tympanic cavity
is moderately wide. Viewed from the external side, the
ventral profile is nearly straight, and the anterior end is
more obliquely truncated than the convexly curved
posterior end.
Little if any correlation was noted between the dimensions
of the bulla and the size of the skull among more than 40
bullae of Calvert cetotheres assembled for comparison.
Tangible differential features that may serve to distinguish
specifically the several species of Calvert cetotheres were
not readily observable. The usefulness of minor or apparent
inconsequential variations in the contour of the bulla for
purposes of identification is certainly questionable in the
present state of our understanding of the developmental
history of these cetotheres.
Measurements (in mm.) of the tympanic bullae are as
follows:
USNM USNM
23690 13472
Left Right
Greatest length of tympanic bulla 76 71.5
Greatest width of tympanic bulla 47 42.5
Greatest vertical diameter of external side, 60 57
ventral face to tip of sigmoid process
Greatest length of tympanic cavity 53 51.5
Periotic
On the type skull (USNM 23690) the posterior processes
of both periotics are firmly lodged in the groove between
the exoccipital and the base of the postglenoid process of
the squamosal. Except for the pars cochlearis of the right
periotic, both periotics are otherwise complete. The left
periotic, whose labyrinthic region apparently is deformed
internally by exostosis, was detached from the type skull.
Both periotics (pl. 51, figs. 1, 2) were detached for examina-
tion from the referred basicranium (USNM 13472).
The rather broad deep groove for the facial nerve (pl.
60, fig. 1) traverses the ventral face of the narrow posterior
process from the external wall of the stapedial fossa to the
extremity of this process. A short obtuse anterior process
projects forward from the bulbous labyrinthic region which
is markedly convex externally but flattened internally.
This swollen anterior portion of the periotic is lodged
as usual in a deep excavation in the squamosal external
to and behind the pterygoid fossa.
The side to side compressed anterior pedicle of the
tympanic bulla was attached to the ventral surface of the
labyrinthic region 10 mm. in advance of the epitympanic
aperture of the Fallopian aqueduct. The broken off basal
portion of the posterior pedicle of the bulla remains
ankylosed to the anterointernal angle of the ventral surface
of the posterior process.
A broad, smooth concave fossa (vertical diameter, 11
mm.; length 27 mm.) extends from the posterorinternal
angle of the posterior process inward across the posterior
face of the pars cochlearis behind the stapedial fossa and above
(dorsal to) the foramen rotunda and its projecting shelf to
the cerebral face of the referred periotic (USNM 13472).
This area is partially concealed by a bony exostotic out-
growth on the type periotic.
170 UNITED STATES NATIONAL MUSEUM BULLETIN 247
As viewed from the ventral aspect the fenestra ovalis is
concealed by the oblique slope of the external face of the
pars cochlearis. A deep narrow groove extends forward and
inward from the fenestra ovalis between the pars cochlearis
and the anterior process. The shallow cavity for reception
of the head of the malleus is located in front of and external
to the epitympanic aperture of the Fallopian aqueduct.
The fossa incudis, which is situated external to the groove
for the facial nerve, is unusually deep and is bounded
internally by a thin elevated rim.
The dome of the pars cochlearis (pl. 60, fig. 2), although
convex is not prolonged ventrally and is not enlarged.
The cerebral face of the pars cochlearis is small. Above the
circular internal acoustic meatus the cerebral face of the
referred periotic is concavely depressed behind and above
an ovoidal rugose depression. The cerebral aperture of the
Fallopian aqueduct is quite large and in close proximity
to the internal acoustic meatus. On the referred periotic
the vestibular aqueduct opens into a large, deep, elongated
depression behind and above the internal acoustic meatus.
Below this depression is the aperture of the small cochlear
aqueduct. The topography of this internal area on the type
periotic, although obscured by exostosis, is identical with
that of the referred periotic.
On another right periotic (USNM 23049) the usual
groove for lodging an extension of the air sac system on the
posterior face of the pars labyrinthica is completely shut off
by an osseous wall from the posterior end of the stapedial
fossa; this malformation resulted from the deep excavation
of the internal end of the posterior process.
Measurements (in mm.) of the periotics are as follows:
USNM USNM USNM
23049 23690 13472
Right Left Left
Length of posterior process, distance 92 87 94
from external wall of stapedial fossa
to extremity
Greatest dorsoventral diameter of 55.5 56 53
periotic from most inflated portion
of tympanic face of pars cochlearis to
most projecting point on cerebral
side
Distance between epitympanic orifice 53 By 45
of Fallopian aqueduct and ex-
tremity of anterior process
Distance from external end of pos- 143 147 143
terior process to anterior end of
anterior process (in a straight
line)
Cervical Vertebrae
The atlas, the right half of the third cervical and a well-
preserved fifth cervical were associated with the type skull
PART 7
(USNM 23690). Both epiphyses were detached from the
third and fifth cervicals, an indication of physical immaturity.
Atlas: Large, moderately thickened anteroposteriorly
(USNM 23690); neural arch with low, rugose, ridge-like
neural crest; high (91 mm.) hourglass-shaped neural canal
(pl. 61, fig. 1); reniform anterior facets for articulation with
occipital condyles of skull deeply concave, slanting obliquely
outward from internal to external margins and separated
ventrally by shallow groove (minimum width, 22 mm.).
On each side the neural arch is pierced, nearer the anterior
than the posterior margin, by a vascular foramen which
opens into a ventrally directed groove. Transverse processes
short, slightly compressed anteroposteriorly and obtuse.
Crescentic posterior articular surfaces (pl. 61, fig. 2)
slightly constricted medially. No hyapophysial process is
developed. An ill-defined upward slanting shallow depres-
sion for reception of odontoid process of axis; forward
projecting median angle of neural arch of axis does not
articulate with neural arch of atlas posteriorly.
Additional measurements (in mm.) of atlas are as follows:
greatest distance between outer margins of anterior articular
facets, 170; greatest distance between outer margins of
posterior articular facets, 180; greatest vertical diameter of
right anterior articular facet, 114; greatest vertical diameter
of posterior articular facet, 104.
Third Cervical: The right side of this cervical (USNM
23690) shows that the centrum was broadly elliptical, the
neural canal unusually wide, and the transverse curvature
of the roof of the neural arch rather gradual. The pedicles
of the neural arch are short, slender and anteroposteriorly
compressed; they support the transversely widened pre-
zygapophysial facets; the somewhat larger postzyga-
pophysial facets (pl. 61, fig. 3) are located on the under
surface of the arch and project backward beyond the level
of the posterior face of the centrum. The slender upper
transverse process (diapophysis) is short, attenuated and
projects outward from the pedicle of the neural arch; the
lower process (parapophysis) is elongated, dorsoventrally
compressed beyond its base. Since the extremities of both
the upper and the lower processes were broken off there is
no certainty that they were united distally to enclose
completely the large cervical extension of the thoracic
retia mirabilia.
Fifth Cervical: The neural canal of this cervical (USNM
23690) is wider than that of the third cervical and the short
pedicles of the neural arch are extended farther ventrally
on the dorsoexternal face of the centrum. The thin roof of
the neural arch (pl. 61, fig. 3) is narrow and from it arises
a very short thin, neural spine. Slender attenuated dia-
pophyses project outward from the pedicles of the neural
arch. The ovoidal prezygapophysial facets are unusually
small; the postzygapophysial facets on the ventral surface
of the neural arch are large and elongate. The roof of the
SHARP-NOSED CETOTHERE 171
neural canal is less elevated (36 mm.) than on the third
cervical (45 mm.) and its width (96 mm.) is greater. The
dorsoventrally compressed parapophysis projects outward
and slightly backward from the ventroexternal angle of the
centrum and is abruptly widened between its base and
acuminate extremity. The extremities of the upper and
lower transverse processes are separated by a wide gap.
Measurements (in mm.) of cervical vertebrae, USNM
23690, are as follows:
Atlas C.3 C.5
Anteroposterior diameter of centrum 58 21> 23.5?
Transverse diameter of centrum 195 — 107.5
anteriorly
Vertical diameter of centrum — 80+ 93
anteriorly
Tip of neural spine to ventral face of 158 138+ 149
centrum anteriorly
Greatest vertical diameter of neural 93 50 36
canal anteriorly
Greatest transverse diameter of neural 49 — 96
canal anteriorly
Greatest distance between outer ends of 237 — 234
parapophyses
Least anteroposterior length of pedicle Sil = 11
of neural arch
Greatest transverse diameter of centrum 185 — 105
posteriorly
Greatest vertical diameter of centrum 114 — 92
posteriorly
>b— Both epiphyses missing.
Dorsal Vertebrae
The vertebra identified as the ninth and eleventh dorsals
were intermingled with lumbar vertebrae which were in
close contact with the ventral surface of the skull.
Ninth Dorsal: On the ninth dorsal (USNM 23690; pl.
63, fig. 1), the broad transverse process (parapophysis),
dorsoventrally thickened at the base, projects outward
from the dorsoexternal surface of the centrum. The antero-
posteriorly expanded (80 mm.) distal end of this process
is thicker posteriorly (16 mm.) than anteriorly (9 mm.)
and is roughened for attachment of the head of the ninth
rib. The metapophyses, which project forward beyond
the level of the anterior face of the centrum, rise at least
60 mm. above the floor of the neural canal and limit ex-
ternally the elongated prezygapophysial facets. Backward
projecting postzygapophysial facets are reduced. The
neural spine (pl. 62, fig. 1) is strongly inclined backward,
but rises at least 125 mm. above the roof of the neural
canal. The pedicles of the neural arch are relatively thin
(minimum width, 14 mm.; the transverse width, 47 mm.,
slightly exceeds the vertical diameter, 45 mm., of the neural
275—-699—68——_6
canal). The profile of the anterior face of the centrum is
definitely subcordate.
Eleventh Dorsal: Extremities of both transverse processes
of this dorsal (USNM 23690) are broken off. At the base
these processes project outward from the ‘external face of
the centrum at a lower level than on the ninth dorsal, but
are likewise dorosoventrally thickened; the anterior edge
is thin and the posterior edge thickened. The pedicles of
the neural arch have increased in anteroposterior diameter
(58 mm.). The thin metapophyses are larger and rise 68
mm. above the floor of the neural canal; they are also less
widely separated. Neither pre- nor postzygapophysial
facets are present. The rather broad (75 mm.) neural
spine, which rises about 130 mm. above the roof of the
neural canal, is strongly inclined backward and truncated
distally. The anterior face of the centrum retains the sub-
cordate profile.
Measurements (in mm.) of the ninth and eleventh dorsal
vertebrae (USNM 23690) are, respectively, as follows:
anteroposterior diameter of centrum, 102, 113; transverse
diameter of centrum anteriorly, 115, 119; vertical diameter
of centrum anteriorly, 90, 93; minimum anteroposterior
length of pedicle of neural arch, 55, 58; transverse diameter
of neural canal anteriorly, 47, 40; vertical diameter of
neural canal anteriorly, 45, 45; distance between ends of
transverse processes, 280=+ ,—; tip of neural spine to ventral
face of centrum posteriorly, 240=+, 250; dorsal edge of
metapophysis to ventral face of centrum anteriorly, 151,
163.
Lumbar Vertebrae
Arranged in serial sequence, the centra of the third to
tenth lumbars increase very gradually in length, width,
and height. No distinct longitudinal median ridge or keel
is developed on the ventral surface of the centra of the six
anterior lumbars (USNM 23690). Notwithstanding the
damaged condition of the parapophyses of the anterior
lumbars, the remnants show that these dorsoventrally
compressed processes diminish in length, but increase in
width behind the seventh lumbar. The vertical diameter
of the neural canal exceeds the transverse on all eight
lumbars. No functional pre- and postzygapophysial facets
are present; the elongated thin lamina-like metapophyses
project forward and more upward than outward. Backward
slanting neural spines increase in anteroposterior width
toward the hinder end of the lumbar series. The minimum
anteroposterior length of the pedicle of the neural arch
diminishes.
Third Lumbar: Increased elevation of the thin lamina
like metapophyses, a greater vertical diameter of the
neural canal, and a more circular profile of the anterior
end of the centrum are the most obvious features distin-
172
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 7
USNM 23690-Lumbar Vertebrae
Anteroposterior diameter of centrum
Transverse diameter of centrum anteriorly
Vertical diameter of centrum anteriorly
Minimum anteroposterior length of pedicle of neural arch
Transverse diameter of neural canal
Vertical diameter of neural canal, anteriorly
Tip of neural spine to ventral face of centrum posteriorly
Dorsal edge of metapophysis to ventral face of centrum anteriorly
L-3 ee tsr—4 lb ey ity Nhaie LER lb)
109> —-:118 104° -115+° 126% 1197 128 129°
118 120 123 121 125 121 121 125
52 56 53 52 48 48 48 46
35 36 35 32 30 30 29 31
52 51 50 46 44 43 42 41
243 2652: 282: 2852 3002: 3202 305-2es2eee
175 167+ 180 175+ 200 195 188 195
a= Anterior epiphysis missing. »>=Both epiphyses missing. >= Posterior epiphysis missing.
guishing the third lumbar (USNM 23690) from the eleventh
dorsal. No material alteration of the oblique backward slant
of the neural spine is observable. A more noticeable dor-
soventral compression of the basal portion of the para-
pophysis characterizes this lumbar and those that follow
in the series.
Fourth Lumbar: This lumbar (USNM 23690) also lacks
the distal end of the backward slanting neural spine whose
anteroposterior width has increased. No change in the
width of the parapophysis at the base is observable.
Fifth Lumbar: This lumbar (USNM 23690) lacks both
epiphyses; the right parapophysis is broken off at the base
as well as the distal ends of the neural spine and the left
parapophysis. As compared with the preceding lumbar,
the width and height of the neural canal have diminished
slightly. The thin lamina-like metapophyses, which rise
80 mm. above the floor of the neural canal, project forward
beyond the level of the anterior face of the centrum, and
their dorsal edges are separated anteriorly by an interval
of 35 mm. The left parapophysis is directed outward and
slightly forward.
Sixth Lumbar: Behind the fifth lumbar the height and
width of the neural canal gradually diminishes to the end
of this series, and so does the minimum anteroposterior
width of the pedicles of the neural arch. The thin meta-
pophyses of the sixth lumbar (USNM 23690) project forward
to but not beyond the level of the anterior face of the
centrum. At both ends of the centrum the transverse dia-
meter exceeds the vertical diameter. The right parapophysis
is broken off at the base, the distal end of the left process is
incomplete, the distal end of the left process is incomplete,
and the anterior epiphysis is missing.
Seventh Lumbar: This lumbar (USNM 23690) lacks the
anterior epiphysis, the distal end of the left parapophysis
and all of the right except the basal portion, and the
extremity of the neural spine. As compared to the pre-
ceding lumbar, the thin metapophyses are less widely sepa-
rated, but rise higher (90 mm.) above the floor of the
neural canal. A distinct median longitudinal keel is devel-
oped on the ventral surface of the centrum.
Eighth Lumbar: Measurements of the centrum (USNM
23690) are not materially different from the seventh lum-
bar. The extremities of both parapophyses are incomplete,
the distal end of the neural spine (pl. 62, fig. 2) is broken
off, and the posterior epiphysis is missing. The left para-
pophysis (pl. 63, fig. 5), which is the most complete, pro-
jects outward and obliquely forward; its distal end seems
to have been expanded. The backward slanting neural
spine is wider anteroposteriorly (85 mm.) than on the
anterior lumbars.
Ninth Lumbar: This lumbar (USNM 23690) lacks the
distal end of the neural spine and the extremities of both
parapophyses are damaged. These subspatulate par-
apophyses were expanded distally and projected less
downward than outward from the lateral surface of the
centrum, their extremities not extending beyond the level
of the anterior face of the centrum. The median longitudinal
keel is very indistinctly developed on the centrum.
Tenth Lumbar: This vertebra (USNM 23690; pl. 62, fig.
3) lacks the distal end of the neural spine and the posterior
epiphysis. The nearly complete left parapophysis (pl. 63,
fig. 3) is dorsoventrally compressed, slightly constricted
near its base, expanded on its distal half and its posterior
edge curved forward to the anteroexternal angle which
extends forward beyond the level of the anterior face of
the centrum. A distinct median longitudinal keel is present
on the ventral surface of the centrum. The profile of the
anterior end of the centrum (pl. 63, fig. 6) is circular. The
thin metapophyses do not extend forward beyond the level
of the anterior face of the centrum.
Measurements (in mm.) of lumbar vertebrae, USNM
23690, are as indicated above.
SHARP-NOSED CETOTHERE 173
BIBLIOGRAPHY
KeELLocc, REMINGTON
1934. The Patagonian fossil whalebone whale, Cetothercum moreni (Lydekker). Contr. Palaeont.,
Carnegie Inst. Washington, publ. 447, pp. 63-81, 2 figs., 4 pls. January 10, 1934.
LyDEKKER, RICHARD
1894. Contributions to a knowledge of the fossil vertebrates of Argentina, II: Cetacean skulls
from Patagonia. Ann. Museo La Plata, Buenos Aires, vol. 2 for 1893, art. 2, pp. 2-4,
p. 1. April 1894.
VaN BENEDEN, PIERRE JOSEPH
1886. Description des ossements fossiles des environs d’Anvers, Part 5; Cétacés. Genres:
Amphicetus, Heterocetus, Mesocetus, Idiocetus and Isocetus. Ann. Mus. roy. d’Hist. nat.
Belgique, Bruxelles, ser. Paléontologique, vol. 13, pp. 139, pls. 75.
8. Supplement to Description of PARIETOBALAENA PALMERI
§ MANY AS EIGHT SPECIES representing four genera of
Recent mysticetes, are or were periodically or season-
ally present off the Atlantic and Pacific coasts of North
America according to recorded historical accounts. Adults
of the little piked whale (Balaenoptera acutorostrata), the
smallest of these Recent mysticetes, range from 22 to 33
feet in length. The blue whale (Balaenoptera musculus),
the largest, measures from 75 to 85 feet off North American
coasts, and as long as 100 feet in Antarctic waters. The
others attain, according to species, lengths from 40 to 75
feet.
Skeletal remains representing six and possibly seven
fossil mysticetes have been recovered from the Calvert
Miocene deposits of Maryland and Virginia. The length
of the smallest of these Calvert cetotheres, Parietobalaena
palmer, did not exceed 14 or 15 feet, and the largest,
**Fischrichtius’’ cephalus, 31 feet by Cope’s estimate. In
addition to the seven free cervicals, so far as is known,
not more than twelve dorsals were present in the vertebral
column; twelve appears to be the maximum number of
lumbar vertebrae and fourteen the number of caudals.
A total of forty five comprised the vertebral column.
Skeletons of adult Recent mysticetes are not only larger,
with one exception, but are also comprised of more ver-
tebrae than the Calvert Miocene cetotheres. This increase
in the number of vertebrae occurs notably in the caudal
series. The vertebral formula is often as follows:
Balaenoptera musculus:
C. 7; D. 15; L. 14; ca. 28 =total 64
B. physalus:
C. 7; D. 15; L. 15; ca. 25 =total 62
B. borealis:
C. 7; D. 13-14; L. 13-15; ca. 20-23 =total 55-57
B. acutorostrata:
Cc. 7; D. 11; L. 12-13; ca. 17-20 =total 49
Eschrichttus glaucus:
C. 7; D. 14; IL, We ca. 23 =total 56
Megaptera novaeangliae:
C. 7; D. 14; L. 10-11; ca. 19-22 =total 51-54
Eubalaena glacialis:
C. 7; D. 14; L. 10-13; ca. 23-26 =total 55-57
The capitulum of each of the seven or eight anterior
pairs of ribs of physically mature individuals of these
Calvert cetotheres has a definite articular contact with a
well-defined facet on the posterolateral surface of the pre-
ceding vertebra. Rib articulation with the centrum of these
anterior dorsal vertebrae has persisted in only one of the
living whalebone whales, the gray whale (Eschrichtius
glaucus). A distinct neck between the tuberculum and
capitulum is present on five or six pairs of the anterior ribs.
The corresponding ribs are unusually robust. This whale
has been observed rolling in kelp beds along the shore and
apparently it is not inconvenienced by occasional strand-
ing in the shallow muddy lagoons of Baja California.
The reduction in the number of ribs having a capitular
articulation with the centrum of anterior dorsals is another
characteristic of Recent balaenopterid whales. Although
three and occasionally four pairs of anterior ribs have a
well-defined neck separating the tuberculum and capit-
ulum, no distinct facet is developed on the centrum for
an articular function.
This reduced capitular articulation by the ribs in the
anterior thoracic region appears to be another one of the
astonishing simplifications of bodily structure resulting
from a long lost requirement for protective support for a
thorax adapted to an exclusively buoyant existence.
Were these large whales not buoyed up by water, their
great weight would collapse the thorax and lungs, causing
suffocation and death.
When cast ashore by incoming tide, a stranded living
whale continues breathing with difficulty until death
ensues; the crushing weight of the anterior portion of the
body on the chest cavity must be lifted by exerting abnormal
175
176 UNITED STATES NATIONAL MUSEUM BULLETIN 247
muscular effort each time air is drawn into the lungs.
A cardiovascular overload results. Intrathoracic pressure
resulting after muscular relaxation impedes the venous
return to the heart in the chest cavity.
On the cetothere skull the supraorbital process of the
frontal slopes gradually downward and outward to the
orbital rim from the level of the dorsal surface of the
interorbital region. On the balaenopterine skull the
supraorbital process of the frontal is abruptly depressed
at the base to a level below the dorsal surface of the inter-
orbital region. This abrupt depression of an originally
sloping supraorbital process makes its appearance geolog-
ically without any transitional or intermediate stage, or
at least none has been described. The mechanical basis
or necessity for this alteration is not readily apparent.
That the Miocene cetotheres were plankton feeders is
certainly indicated by the grooves on the ventral rostral
surface of the maxillaries which on skulls of Recent whale-
bone whales serve as channels for the vascular vessels and
nerves supplying the lateral rows of baleen.
Among Recent mysticetes two general tendencies in the
remodeling of skull architecture are noted. One end result
is largely limited to the forward movement or thrust of
the posterior cranial elements (Balaenidae), carrying the
apex of the supraoccipital shield forward beyond the
orbit and the associated very slight or limited backward
movement of the rostral elements, the nasal bones being
located entirely in front of the supraorbital processes of
the frontals.
In the other type of remodeling (Balaenopteridae), the
median rostral elements (ascending processes of maxillaries
and premaxillaries and the nasals) in a backward move-
ment override the frontals to or usually beyond the level
of the preorbital angle of the supraorbital process of the
frontal.
Among the Miocene antecedents of the Recent mysticetes
are several types of interdigitation, including skulls on
which the nasals are either almost entirely or only partially
located anterior to the preorbital angle of the supraorbital
process of the frontal, as well as either limited or extensive
backward overriding by the median rostral elements.
PARIETOBALAENA Kellogg
Parietobalaena Kellogg, 1924, Proc. U.S. Nat. Mus., vol. 63,
publ. 2483, p. 1. February 5, 1924.
Type species: Parietobalaena palmeri Kellogg.
Diagnosis: Parietals meet medially to form a ridge be-
tween the apex of the supraoccipital shield and the frontals;
maxillary, premaxillary, and nasal sutural contact grooves
extended backward on frontals beyond level of preorbital
angle of supraorbital process; rostrum tapering toward
PART 8
extremity; transverse temporal crest developed on supra-
orbital process of frontal on mature skulls; nasals located
for most part anterior to level of preorbital angle of supra-
orbital processes; zygomatic process of squamosal slender,
attenuated anteriorly and extended forward to or almost
to elongated postorbital projection of supraorbital process
of frontal; postglenoid process directed more downward
than backward, flattened on its posterior face and rounded
distally; occipital condyles small; exoccipitals directed
obliquely downward and backward, with lateral end pro-
jecting backward beyond level of articular surface of condyle
on adult skulls; pars cochlearis of periotic with strongly con-
vex dome or apex extended ventrally; a short narrow fossa
of variable depth behind rim of fossa for stapedial muscle
and above fenestra rotunda and its projecting shelf extends
across posterior face of pars labyrinthica to its cerebral face.
Tympanic bulla and periotic resemble in some details those
of ‘‘Idiocetus” laxatus Van Beneden (1886, pl. 54, figs. 3-4).
A deep groove for attachment of internal pterygoid muscle
present below articular surface of condyle and above angle
on internal surface of posterior end of mandible.
PARIETOBALAENA PALMERI Kellogg
Parietobalaena palmeri Kellogg, 1924, Proc. U.S. Nat. Mus., vol. 63,
publ. 2483, p. 2.
Type specimen: USNM 10668. A cranium of a fairly
young individual in a fair state of preservation; the nasals,
jugals, and lachrymals, as well as the rostrum and its com-
ponent parts, the maxillaries, premaxillaries, and vomer,
are missing. Both periotics are attached to the cranium;
incomplete left tympanic bulla is detached. Collector,
William Palmer; August 14, 1913.
Type locality: From face of cliff near center of zone 11
and about 3 feet above beach level, approximately 1 mile
north of Dares Wharf, Calvert Co., Md., Calvert formation,
middle Miocene.
Referred specimens: Twenty, as follows: (1) USNM
7424: posterior end left mandible, length 395 mm., coll.
William Palmer and A. C. Weed, May 31, 1912, in zone
11 at base of cliff about 150 yards north of old pier at
Dare’s wharf, Calvert Co., Md., Calvert formation,
middle Miocene. (2) USNM 10677: skull, right and left
mandibles, right tympanic bulla, right periotic, 18 ribs
and fragments, coll. William Palmer and Norman H. Boss,
September 1908, in zone 10 at base of cliff about % mile
south of Plum Point wharf, Calvert Co., Md., Calvert
formation, middle Miocene. (3) USNM_ 10909: basi-
cranium, portions of rostrum, periotics, coll. David B.
Mackie, Aug. 10, 1908, in zone 10, about 2 miles south of
Plum Point wharf, Calvert Co., Md., Calvert formation,
middle Miocene. (4) USNM 11535: cranium and portions
of maxillaries, premaxillaries and vomer, both tympanic
PARIETOBALAENA PALMERI
bullae, both periotics, right mandible, humerus, 6 cervicals,
1 dorsal, 1 caudal, 2 phalanges, and 10 ribs and fragments,
coll. Norman H. Boss and Remington Kellogg, May 23,
1926, in zone 11, about a mile south of Plum Point wharf,
Calvert Co., Md., Calvert formation, middle Miocene.
(5) USNM 12697: right and left mandibles, atlas, 1
cervical, 5 dorsals, 5 lumbars, 3 caudals, 5 epiphyses,
radius and ribs, coll. William Palmer and Norman H. Boss,
Dec. 6, 1913, in zone 10, about % mile south of Plum
Point wharf, Calvert Co., Md., Calvert formation, middle
Miocene. (6) USNM 13874: hinder portion of basicranium,
right and left tympanic bulla, right and left periotic, and
atlas, coll. R. Lee Collins, Mar. 24, 1936, in zone 11,
about 8 feet above base of cliff, one mile south of Plum
Point wharf, Calvert Co., Md., Calvert formation, middle
Miocene. (7) USNM 13903: left mandible, lacking condyle,
coll. Wm. F. Foshag and Charles W. Gilmore, July 12,
1936, in zone 12, about 600 feet south of mouth of Parker
Creek, Calvert Co., Md., Calvert formation, middle
Miocene. (8) USNM 15576: left tympanic bulla, with
malleus attached, coll. S. F. Blake, Mar. 27, 1938, in zone
16, about 3 feet above base of cliff at Calvert Beach, Calvert
Co., Md., Choptank formation, middle Miocene. (9)
USNM 16119: skull and portion of rostrum, right and
left tympanic bulla; right and left periotic, 1 rib, coll.
Wm. F. Foshag and Remington Kellogg, July 15, 1939,
in zone 12, %o mile north of mouth of Parker Creek,
Calvert Co., Md., Calvert formation, middle Miocene.
(10) USNM 16568: right and left tympanic bullae, right
and left periotics, portions of skull, right and left mandible,
axis, 3 cervicals, 2 lumbars, coll. Wm. F. Foshag and
Remington Kellogg, Aug. 5, 1940, in zone 12, 625 yards
south of mouth of Parker Creek, Calvert Co., Md., Calvert
formation, middle Miocene. (11) USNM 16570: skull,
right mandible, right periotic, 1 dorsal, 1 caudal, fragments
scapula, coll. Charles W. Gilmore, Wm. F. Foshag, H. S.
Bryant, and Remington Kellogg, June 7, 1940, in zone 12,
695 yards south of mouth of Parker Creek, Calvert Co., Md.,
Calvert formation, middle Miocene. (12) USNM 16667:
axis, 1 dorsal, 2 lumbars, 11 caudals, coll. Wm. F. Foshag
and Remington Kellogg, July 17, 1941, in zone 10, about
1 mile south of Plum Point wharf, Calvert Co., Md.,
Calvert formation, middle Miocene. (13) USNM 16838:
Cranium, right and left tympanic bulla, right and left
periotic, portions of rostrum, coll. R. Lee Collins, June 10,
1937, in zone 10, one and % miles south of Plum Point
wharf, Calvert Co., Md., Calvert formation, middle
Miocene. (14) USNM 20376: right and left tympanic
bulla, right and left periotic, squamosals, coll. W. Gardner
Lynn, Nov. 4, 1933, about 1 mile south of Plum Point
wharf, Calvert Co., Md., Calvert formation, middle
Miocene. (15) USNM 23015: right tympanic bulla, right
periotic, right squamosal, coll. A. C. Murray and John
177
George, in zone 12, 700 yards south of mouth of Parker
Creek, Calvert Co., Md., Calvert formation, middle
Miocene. (16) USNM 23022: skull, both tympanic
bullae, both periotics, coll. James R. Switzer, March 1958,
in zone 13, 700 yards north of road end at Governor Run,
Calvert Co., Md., Calvert formation, middle Miocene.
(17) USNM 23055: right and left tympanic bulla, left
periotic, portions of skull, right mandible, axis, 1 cervical,
5 dorsals, 1 caudal, portions of ribs, coll. Howard Hruschka,
Nov. 17, 1963, in zone 13, 500 yards north of road end at
Governor Run, Calvert formation, middle Miocene. (18)
USNM 23203: posterior end right mandible, portions of
skull, atlas, axis, 5 cervicals, 12 dorsals, 10 lumbars, 9
caudals, 2 chevrons, coll. Robert E. Weems, July 4, 1964,
about 3.6 miles below mouth of Pope’s Creek, Stratford
Bluffs, Westmoreland Co., Va., Calvert formation, middle
Miocene. (19) USNM 23448: 4 dorsal vertebrae, portions
of ribs, coll. Albert C. Myrick, Jr., Feb. 13, 1965, in zone
14, 350 yards north of road end at Governor Run, Calvert
Co., Md., Calvert formation, middle Miocene. (20) USNM
23725: skull, coll. Albert C. Myrick, Jr. and Charles F.
Buddenhagen, June 1, 1966, in zone 10, Holland Cliffs,
on Patuxent River, about % mile north of Deep Landing,
Calvert Co., Md., Calvert formation, middle Miocene.
Skull
The major portion of the left side of the restored skull
(USNM 10677), now exhibited in the vertebrate paleon-
tology hall of the United States National Museum, was
destroyed prior to excavation. The length of this skull
(pl. 65, fig. 3) is 1115 mm. Another skull (USNM 23022)
possesses a fairly complete braincase, both zygomatic
processes and the premaxillaries, but lacks the supra-
orbital processes as well as the external borders of both
maxillaries. This skull (pl. 64, fig. 2) measures 1200 mm.
in length. Another skull (USNM 16570; pl. 64, fig. 3)
measuring 1250 mm. in length lacks the right zygomatic
process and adjacent portion of the cranium, the major
portions of both supraorbital processes, and most of the
left side of the rostrum. The largest skull (USNM 11619;
pls. 66 and 67) has a fairly well-preserved braincase and
both zygomatic processes, but lacks most of the supra-
orbital processes and retains only portions of the rostral
elements.
Dorsat virw.—The skulls of this cetothere represent
a less advanced stage in the modification of skull archi-
tecture by either forward or backward overriding of ad-
jacent bones. On the skulls of young or adolescent in-
dividuals of this species the posterior ends of the median
rostral elements extend backward to or slightly beyond the
level of the preorbital angles of the supraorbital pro-
cesses. With approach or attainment of physical maturity
178 UNITED STATES NATIONAL MUSEUM BULLETIN 247
Pmx.
Vo.
ant.
E%X.06.
Ficure 77.—Dorsal view of skull, USNM 16119, of Parietobalaena
palmeri Kellogg. Reconstruction based on four skulls. For
abbreviations, see figure 79.
PART 8
these median rostral elements (fig. 77) are extended back-
ward nearly to the level of the center of the orbit.
In front of the nasal fossa (USNM 23022; length, 260+
mm.) in the narrow mesorostral trough, the premaxillaries
are in contact to their anterior ends. In front of the anterior
end of the vomer (USNM 23022; length, 785 mm.), which
terminates 310 mm. behind the extremity of the right
premaxillary of this skull the opposite maxillaries do not
meet on the midline to contribute the bottom of the me-
sorostral trough. The internal surface of each premax-
illary, however, is concavely curved downward to form
the dorsal portion of the lateral wall of the mesorostral
trough.
Each premaxillary (USNM 16570) attains its maximum
width (45 mm.) at the level of the anterior ends of the
corresponding maxillary. The posterior ascending portion
of each premaxillary rests in a narrow groove on the
dorsointernal border of the adjacent maxillary and is
lodged at the hinder end in the narrow grooves on the dorsal
surface of the frontal. Dorsally, each relatively thin pre-
maxillary is narrowed alongside the nasals. On each side
the premaxillary follows the curvature of the nasal fossa
and then progressively increases in depth and width. On
the anterior three fourths (600+ mm.) of the length of the
rostrum (800+ mm.) the dorsal surfaces of the premax-
illaries are noticeably flattened. Poorly preserved nasal
bones are present on two skulls (USNM 10677, 16119);
they are detached and lost from all other skulls of this
species in the collection. On the above-mentioned skulls,
the grooves for sutural contact on the frontals and the in-
terval between the posterior ends of the opposite premax-
illaries also indicate their width.
This skull is also characterized by a narrow tapered
rostrum, equivalent to two-thirds of the length of the skull
(occipital condyle to end of premaxillary); slender zygo-
matic process; narrow postglenoid process; moderate
forward thrust of the supraoccipital shield, the dorsal half
being narrowed toward the acuminate apex; a sharp-
edged intertemporal ridge formed by parietals at contact
on midline; and wide temporal fossa.
The apex of the supraoccipital shield (fig. 77) projects
forward to or beyond the level of the anterior ends of the
zygomatic processes and these slender processes are di-
rected obliquely outward and forward.
Each maxillary is abruptly widened at the base by the
posteroexternal basal angle that projects laterally beyond
the preorbital angle of the supraorbital process on Recent
mysticete skulls. The lachrymal, which normally is lodged
on the posterior face of this angle was not preserved. The
thin lateral edge of each maxillary is slightly curved toward
its anterior end. Except for its posterointernal extremity,
each maxillary does not override the superaorbital process
of the frontal dorsally, but does along the anterior border
PARIETOBALAENA PALMERI
ventrally. Two to four small nutrient foramina are located
near the contact with the premaxillary on the posterior
half of each maxillary. Jugal bones were not associated
with any of these skulls.
SW
N
Ficure 78.—Dorsal view of skull, USNM 10677, of Partetobalaena
palmeri Kellogg. For abbreviations, see figure 79.
179
Between the intertemporal region contributed by the
parietals and the posterior ends of the rostral bones, the
frontal bones (USNM 10677; fig. 78) are exposed for an
interval of less than 15 mm. Each frontal slopes gradually
downward from the midline behind the nasals to the orbital
rim of the supraorbital process of the frontal. The transverse
ridge or crest is low and indistinctly developed on the
supraorbital processes of all the skulls. Whether or not the
rounded preorbital angle of the supraorbital process pro-
jected outward beyond the lateral extensions of the postero-
external end of the maxillary cannot be determined since
this region is missing on all the skulls. The stout postorbital
projection of the supraorbital process is extended backward
to the anterior end of the zygomatic process.
The opposite parietals meet on the midline of the cranium
to constitute a sharp-edged ridge; they are also overlapped
above and behind by the lateral borders of the supraoccipital
shield. The thin anterior border of each parietal overlaps the
interorbital basal portion of the corresponding frontal.
On each side the posteroventral portion of the braincase
is constituted by the squamosal. Behind its contact with the
pterygoid, the squamosal follows the curvature of the
ie
Yi Wy Yyy
ess
FicureE 79.—Dorsal view of skull (type), USNM 10668, of
Parietobalaena palmeri Kellogg. Abbrs.: ant. n., antorbital
notch; Bo., basioccipital; Bs., basisphenoid; c., occipital condyle;
Ex.oc., exoccipital; fm., foramen magnum; f.max., maxillary
foramen or incisure; f.ov., foramen ovale; Fr., frontal; h.pt.,
hamular process of pterygoid; j.n., jugular notch or incisure;
1. pr., lateral or descending protuberance of basiocipital; Max.,
maxilla; m.e.a., channel for external auditory meatus; Na.,
nasal; 0.c., optic canal; Pa., parietal; Pal., palatine; pgl.,post-
glenoid process; Pmx., premaxilla; pr.a., anterior process of
periotic; pr.p., posterior process of periotic; pr.s.p., presphenoid;
Pt., pterygoid; pt. f., pterygoid fossa; S.oc., supraoccipital;
Sq., squamosal; s.or.pr., supraorbital process of frontal; Ty.,
tympanic bulla; Vo., vomer; zyg., zygomatic process.
180
temporal fossa to the extremity of its zygomatic process.
This slender zygomatic process is directed obliquely outward
and forward to or almost to the end of the postorbital
projection of the supraorbital process. The lambdoidal
crest is continued forward on the dorsal edge of the zygo-
matic process.
Except at their extremities the exoccipitals on skulls of the
immature individuals (fig. 79) are largely concealed from
a dorsal view; the occipital condyles project backward
beyond the level of the ends of the exoccipitals. On skulls
of older individuals (fig. 77) the exoccipitals project back-
ward beyond the level of the articular surfaces of the occi-
pital condyles. The transverse diameter (250 mm.) of the
triangular occipital shield on the largest skull (USNM
16119) at the level of the dorsal rim of the foramen magnum
Ficure 80.—Posterior view of skull (type), USNM 10668, of
Parietobalaena palmert Kellogg. For abbreviations, see figure 79.
exceeds the greatest distance (195 mm.) from the dorsal
rim of this foramen to the apex of this shield. On another
skull (USNM 23022) these measurements are, respectively,
220 and 190 mm. The transverse diameter of this supra-
occipital shield is progressively reduced above the middle
of its height to the apex.
PosTERIOR view.—The ratio of height to the width of the
braincase diminishes with growth and the exoccipitals
become extended farther laterally. Depression of the top
of the braincase increases with age.
The broad supraoccipital constitutes the major portion of
the triangular shield which curves upward and forward.
On the cranium (USNM 10668; fig. 80) of the young whale
this shield from a posterior view appears more rounded
than it is actually. The lambodidal crest (fig. 81) constituted
by the lateral margins of the supraoccipital and exoccipital
and the abutting edges of the parietals and squamosals,
increases in prominence toward the apex of the shield;
laterally it continues forward along the dorsal edge of the
zygomatic process.
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 8
The occipital condyles are semi-elliptical in outline,
broadest above the middle of their height, and their
articular surfaces are convex in both vertical and transverse
directions. The occipital condyles are less protuberant on
the adult skull than on that of the young. Each postglenoid
process is prolonged ventrally, flattened on its posterior face,
and rounded distally.
Ficure 81.—Posterior view of skull, USNM 16119, of Partetobalaena
palmeri Kellogg. For abbreviations, see figure 79.
LATERAL viEW.—The highest point in the dorsal profile
(USNM 10677; pl. 64, fig. 3) is behind the apex of the
supraoccipital shield. In front of the apex, the intertemporal
ridge slopes to the flattened median interorbital region;
between this median region and the extremity of the rostrum
the slope of the dorsal profile is very gradual. The greatest
dorsoventral diameter of the rostrum is at the hinder end
of the nasal fossa. The convex side to side curvature of the
dorsal surface of the rostrum is gradually diminished
toward the extremity; the ventral surface of the rostrum is
quite flat on the distal one third.
The orbital border of the supraorbital process of the
frontal is dorsoventrally compressed and shallowly arched.
Elongation of the postorbital projection has lengthened the
orbit and shortened the interval between the ends of this
projection and the attenuated slender zygomatic process.
The postglenoid process extends more downward than
backward, its glenoid surface being slightly convex.
From a lateral view the contact of the parietal with the
squamosal is almost horizontal ventrally and nearly vertical
posteriorly. The opposite parietals meet on the midline of
the intertemporal region, forming a sharp-edged ridge. On
quite young skulls (USNM 16838), the ovoidal external end
of the alisphenoid is located on the outer wall of the brain-
case between the pterygoid ventrally and the parietal.
On more mature skulls (USNM 23022) the alisphenoid is
more elongated and dorsoventrally compressed. In de-
scribing the relations of the bones in this region, Ridewood
(1922, p. 262) comments that among mammals it is unusual
PARIETOBALAENA PALMERI
Ficure 82.—Ventral view of skull, USNM 16119, of Parietobalaena
palmeri Kellogg. For abbreviations, see figure 79.
181
for the squamosal to extend forward to meet the pterygoid,
as it does on mysticete skulls, as is also the location of the
foramen ovale in a cleft at the end of the squamosal behind
the pterygoid.
The occipital condyles are not visible when the skull is
viewed from the side.
VENTRAL VIEW.—Description of the ventral aspect of
the skull will of necessity be based on several specimens.
The ventral surface of the cranium is best preserved on
USNM 16119 (fig. 82); the relations of several individual
bones are well defined on a young skull (USNM 10668),
and the rostral bones are fairly complete on USNM 10677.
Of the several bones comprising the skull, the largest is
the maxillary, which except for the thin proximal border is
sufficiently complete on the right side of an immature skull
(USNM 10677; pl. 65, fig. 4) to show the arrangement of
the grooves for the nutrient vessels that supply the palate
and the attached baleen. Most of these grooves are located
on the flattened ventral surface external to the median
downward curved internal border that is applied to the
trough of the vomer. The longest of these grooves (fig. 83)
are located chiefly on the anterior half of the rostrum and
they are directed more forward than the shorter and more
numerous oblique grooves. A few shorter curved grooves
directed more transversely than those elsewhere on the
palatal surface are present near the proximal end of the
rostrum.
The vomer on the skull (pl. 65, fig. 4) is fortuitously
exposed ventrally, by the separation of the maxillaries,
for nearly its entire length on the rostrum. On all these
skulls, a downward directed median vertical partition,
mainly arising from the horizontal vaginal plate of the
vomer and separating the choanae, diminishes in height
behind the median divergence posteriorly of the opposite
palatines. On the largest skull (USNM 16119), the flat
ventral edge of this partition becomes visible 120 mm. in
front of the posterior edge of the horizontal vaginal plate
of the vomer and vanishes about 25 mm. anterior to this
edge. This horizontal plate conceals, when present, the
transverse ankylosis of the basioccipital and basisphenoid
and also the sutural contact of the latter with the presphenoid
(fig. 84). Laterally this horizontal plate is suturally in
contact with the corresponding edge of the vaginal process
of the pterygoid. The trough of the vomer is widest near
the level of the anterior ends of the palatines.
Each elongated palatine meets its opposite on the midline,
is applied to the ventral surface of the trough of the vomer,
is in contact anteriorly and externally with the correspond-
ing maxillary, and, posteriorly, is suturally united with the
pterygoid. The posterior divergence of the posterointernal
edge of the palatine commences on the vertical partition
between the choanae about 120 mm. in front of the posterior
edge of the vaginal plate of the vomer. The anteroposterior
182
Ficure 83.—Ventral view of skull, USNM 10677, of Partetobalaena
palmeri Kellogg, restored. For abbreviations, see figure 79.
UNITED STATES NATIONAL MUSEUM BULLETIN 247
PART 8
diameter of the palatine is equivalent to about 17 (USNM
16570) to 20 percent (USNM 10677; fig. 83) of the length
of the skull.
The supraorbital processes of the frontals are incomplete
on all skulls except the young specimen (USNM 10668).
On one (USNM 10677), the outer portion of the right
process is well preserved (pl. 65, fig. 4). The preorbital
angle of this process is rounded and the postorbital is ex-
tended backward to the end of the zygomatic process. On
the young skull (fig. 84; USNM 10668) the channel for the
optic nerve curves outward on the ventral surface of the
supraorbital process of the frontal in the usual manner and
increasing in width becomes widest at the orbital rim. Near
Ficure 84.—Ventral view of skull (type), USNM 10668, of
Parietobalaena palmert Kellogg. For abbreviations, see figure 79.
its origin this channel is located on the posterior surface of
this process but twists downward to the ventral surface and
then on its outward course is located behind the well-
defined anterior wall.
The ventral surface of the relatively narrow basioccipital
is shallowly concave. On each side of this bone the lateral
descending protuberance, although variable in shape pos-
sibly attributable to age, is convex internally and over-
lapped anteriorly by the vaginal process of the pterygoid.
The basioccipital is so intimately fused with the basisphe-
noid, even on the young skull (USNM 16838), that the
sutural contact is obliterated. A narrow gap separates the
alisphenoid and the presphenoid at least until physical
maturity. Both the alisphenoid and the presphenoid are
hidden from a ventral view by the overspreading ventral
horizontal plate of the vomer.
PARIETOBALAENA PALMERI
The pterygoid is intercalated between the posterior end
of the palatine and the bifurcated anterior end of the
squamosal. This bifurcation of the squamosal encloses the
foramen ovale.
The relatively small pterygoid fossa is constituted by the
vaginal process of the pterygoid internally, anteroexternally
by the ventrally curving thickened anterior and external
borders of the pterygoid, and to a limited extent postero-
externally by the falciform process of the squamosal. The
pterygoid contributes the osseous roof of this fossa. This
pterygoid fossa is continuous posteriorly with the tympano-
periotic recess, which is bounded by the squamosal ex-
ternally, by the pterygoid anteriorly, by the lateral pro-
tuberance of the basioccipital internally, and by the
exoccipital posteriorly. A broad notch or incisure on the
exoccipital at the posterior end of this recess constitutes the
posterior lacerated foramen for the jugular leash.
On the ventral surface the contact between the exoccipital
and the squamosal is concealed by the posterior process of
the periotic, which is securely lodged in a transverse groove
on the squamosal behind the postglenoid process of the
squamosal. At the base of the postglenoid process and
anterior to the posterior process of the periotic is the trans-
verse groove or channel for the external auditory meatus.
On the ventral edge of the exoccipital external to the jugular
notch is a narrow depression which constitutes the paroccip-
ital process or area for attachment of the stylohyoid.
The slender anteriorly attenuated zygomatic process is
directed outward and forward. The postglenoid process is
not enlarged or thickened and is deflected obliquely back-
ward. The flattened posterior surface of the postglenoid
process contrasts strongly with the convexity of its anterior
surface and the internal concave area on the adjacent
ventral surface of the squamosal.
The skull (MHNB 4018) identified by Abel (1938, p. 28,
fig. 4) as Isocetus depauwit has 420 mm. zygomatic width.
As compared to this Calvert cetothere, the Belgian skull is
characterized by a strongly attenuated and much narrower
rostrum throughout its length; the zygomatic process is also
more robust. Furthermore, the Belgian skull is distinguished
by a somehwat different profile of the temporal fossa when
viewed from the ventral side, the zygomatic process being
turned forward abruptly almost at a right angle from the
anterior temporal surface of the squamosal. A deep crease
at this point on the anterior border of the squamosal
distinguishes skulls of recent Balaenoptera.
Measurements (in mm.) of the skull are as follows:
USNM USNM
16119 10677
Greatest length of skull, anterior end of right 1280+ 1100
premaxillary to level of posteroexternal
angle of right exoccipital
Distance from anterior end of right pre-
maxillary to posterior articular face of right
occipital condyle
Distance from anterior end of right pre-
maxillary and extremity of right postglenoid
process
Distance from anterior end of right pre-
maxillary and apex of supraoccipital shield
Greatest length of right premaxillary
Distance from apex of supraoccipital shield to
posterior end of right nasal bone
Transverse diameter of skull across preorbital
angles of supraorbital processes
Greatest anteroposterior diameter of extremity
of right supraorbital process of frontal
Transverse diameter of skull across outer sur-
faces of zygomatic processes
Transverse diameter of skull between outer
edges of exoccipitals
Transverse distance between outer edges of
occipital condyles
Greatest or obliquovertical diameter of right
occipital condyle
Greatest transverse diameter of right occipital
condyle
Greatest transverse diameter of foramen
magnum
Distance from dorsal rim of foramen magnum
to apex of supraoccipital shield
Distance from anterior end of right pre-
maxillary to anterior end of right nasal bone
Greatest length of right nasal bone
Transverse diameter of anterior end of right
nasal bone
Transverse diameter of posterior end of right
nasal bone
Combined width of nasal bones, anteriorly
Greatest transverse distance between outer
margins of premaxillaries at level of anterior
ends of maxillaries
Greatest breadth of basioccipital across lateral
protuberances, outside measurement
Greatest length of left zygomatic process, ex-
tremity of postglenoid process to anterior
end
Greatest anteroposterior diameter of left
palatine
Greatest transverse diameter of left palatine
Distance from posterior surface of right oc-
cipital condyle to posterior end of vomer
Distance from posterior surface of left occipital
condyle to anterior edge of left palatine
Posterior edge of vomer to anterior edge of
left palatine
USNM
16119
1260+
1240+
214
225
60+
120
390
273
184 UNITED STATES NATIONAL MUSEUM BULLETIN 247
Ficure 85.—Views of left tympanic bulla and malleus, USNM
15576, of Parietobalaena palmeri Kellogg: a, dorsal view; 6,
external view. Abbrs.: a.c., orifice of cochlear aqueduct;
a.i.c.F., internal aperture of aquaeductus Fallopii; a.p., anterior
pedicle of bulla; a.v., orifice of vestibular aqueduct; c.f., channel
for facial nerve; f.a.s., fossa for extension of air sac system;
f.c.m., fossa for head of malleus; fe.o., fenestra ovalis; fe.r.,
fenestra rotunda; inv., involucrum; m., malleus; m.a.i., internal
acoustic meatus; p.c., pars cochlearis; p.p., posterior pedicle
of bulla; pr.a., anterior process (pro-otic); pr.m., processus
medius or conical apophysis; pr.p., posterior process (opisthotic) ;
pr.s., sigmoid process; t.s.f., tractus spiralis foraminosus.
PART 8
Tympanic Bulla
An undamaged tympanic bulla attached to the right
periotic (USNM 13874), which was associated in the
Calvert zone 11 with the hinder part of the basicranium
and a left tympanic bulla with complete attached malleus
(USNM 15576) found isolated from other skeletal elements
in the Choptank zone 16 are the best preserved of twelve
bullae referred to this species. The left tympanic bulla,
which was associated with the type cranium (USNM 10668)
of Parietobalaena palmeri in the Calvert zone 11 lacks a
portion of the thin outer lip, the anterior pedicle, the
sigmoid process, and the normally attached malleus.
This bulla (greatest length, 57 mm.) is slightly smaller
than either the above mentioned right bulla (USNM
13874; greatest length, 60.5 mm.) or another right bulla
(USNM 10677; greatest length, 59 mm.) detached from a
skull (length, 1107 mm.) excavated in Calvert zone 10.
The posterior pedicle (fig. 86a), located transversely on
the tympanic bulla, is much thicker where it is ankylosed
to the periotic than the thin longitudinal attachment of the
anterior pedicle. This posterior pedicle may or may not
be separated by a cleft from the low, blunt posterior conical
apophysis (fig. 86a); in either condition it arises internally
from the posterior end of the thickened involucrum and
externally at the posterior end of the outer lip.
Viewed from the ventral aspect the posterior end of the
bulla is obliquely truncated in an internoexternal direction,
the transverse diameter of the anterior end is less than the
posterior end, and a low faintly defined ridge extends
obliquely from the posteroexternal angle to the antero-
internal angle.
The thin overarching outer lip, whose anterior pedicle
is ankylosed to the anterior process of the periotic, does
not by its curvature abruptly reduce the width of the
eustachian outlet of the tympanic cavity. The width of the
involucrum (fig. 86a) is strongly diminished at its anterior
end and transverse creases are indistinct except near the
eustachian outlet.
Referring again to the outer lip, it would appear that
some functional demand existed for twisting the rounded
and thickened sigmoid process (fig. 85b) at right angles
to the longitudinal axis of the bulla as well as for the pres-
ence of a deep groove between it and the posterior conical
apophysis. The slender stalk-like anterior process of the
malleus (fig. 85a) was attached in the normal position
along the posterior border of the sigmoid process.
Viewed from the external aspect (fig. 86b) the depth
of the rounded posterior profile exceeds that of the less
convex anterior end.
Accumulation of a representative series of tympanic
bullae during the past forty years from the Calvert forma-
tion, some isolated and others associated with crania, has
shown that their lengths do not provide a reliable basis
PARIETOBALAENA PALMERI
for identification. Lengths of the bullae of this species range
from 52 to 63 mm. Other minor differences may be attrib-
uted to age factors.
Measurements (in mm.) of the tympanic bullae are as
follows:
USNM USNM USNM USNM USNM
10668 16119 10677 13874 15576
Left Right Right Right Left
Greatest length of bulla 5759.5 59 60.5 62.5
Greatest width of bulla = 34.8 36 35 33
Greatest vertical diameter = 48 43.5 45 49
on external side, ventral
face to tip of sigmoid
process
Greatest length of tym- AA 2 44 41.5 46
panic cavity
Periotic
Likeness of cetothere periotics without some degree of
relationship seems unlikely. The degree of affinity may be
assessed by noting the extent of resemblance of auditory
structures that appear to be less susceptible of modification
during growth. For example the shape of the pars cochlearts
of this species exhibits very little change in the growth
stages from new born to adult. The most obvious alteration
occurs in the shape and dimensions of the posterior process
(fig. 84), which is firmly wedged in a deep groove between
the exoccipital and the postglenoid portion of the squamosal.
Nine periotics either attached to or associated with skulls
or crania were selected to illustrate the range of individual
variation. A similar type of pars cochlearts is found in the
Belgian Anversian ‘‘Jdiocetus” laxatus (Van Beneden, 1886,
pl. 54, figs. 3, 4).
On the posterior face of the pars cochlearis above (dorsal to)
the foramen rotunda and its projecting shelf and behind the
stapedial fossa is a short, narrow fossa (vertical diameter,
4 to 8 mm.) of variable depth that extends from the internal
end of the posterior process to the inner (cerebral) face
of the periotic (fig. 87b). It is separated from the fossa
for the stapedial muscle by the thin crestlike posterior
ridge bounding the latter. This fossa extends upward and
inward from the fossa for the stapedial muscle.
The fars cochlearis is relatively small, compressed slightly
from, side to side (fig. 88a), somewhat triangular in profile
when viewed from the internal (cerebral) side; the dome
or apex of the pars cochlearis (fig. 88b) is conspicuously
extended ventrally. No discernible alteration in the size
of the pars cochlearis during growth was noted among these
periotics. The cerebral face of the labyrinthic region dorsal
to the internal acoustic meatus is variable in appearance,
smooth (flat or concave) or porous and rugose (USNM
16119).
On the internal face, the internal acoustic meatus is
small, usually somewhat circular in outline at level of the
185
pr.m.
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a | « !
Sh
Fart
“Yd
HEAT Wii,
Se
Se
SS
Ps
“ «
pr. Se WY
Ficure 86.—Views of right tympanic bulla, USNM 10677, of
Parietobalaena palmeri Kellogg: a, dorsal view; b, external view.
For abbreviations, see figure 85.
cerebral rim, but occasionally ovoidal; this rim is 9 to 14
mm. above (dorsal to) the dome of the pars cochlearis. The
vestibular aqueduct (fig. 87b) opens into an elongated or
broad ovoidal depression of variable depth on the cerebral
face. The cerebral aperture of the Fallopian aqueduct is
either adjacent to the rim of the internal acoustic meatus
(USNM 13874), at the anterodorsal angle of the fars
cochlearis (USNM 10909; pl. 48, fig. 6), or small and within
the cerebral rim of the internal acoustic meatus (USNM
20376).
The shape of the posterior process (opisthotic) appears
to be quite variable, and this variation may not be entirely
186 UNITED STATES
NATIONAL MUSEUM BULLETIN 247
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‘Wie Y,
if oy ©
WZ J &
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4
iN ff
X We
NES
wi Tiin 22>
ee MAS
a y M51 GY SSS
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Ficure 87.—Views of right tympanic bulla and periotic,
USNM 13874, of Par;
etobalaena palmeri Kell
view. For abbreviations, see figure 85,
88: @, external view; 4, internal
PART 8
PARIETOBALAENA PALMERI 187
attributable to age. On most skulls the posterior process
(fig. 88b) is relatively short and abruptly expanded beyond
the base; on others it is either gradually enlarged toward
the extremity or slender and elongated (pl. 48, fig. 6).
The posterior pedicle of the tympanic bulla (fig. 87a)
before it was dislodged or broken off while in storage was
ankylosed with the anterointernal angle of the posterior
process. Behind this pedicle, the groove for the facial nerve
extends outward toward the extremity of the ventral face
of this process. The series of crania now available indicate
pC. ES
Ficure 88.—Views of right periotic (type), USNM 10668, of
Parietobalaena palmeri Kellogg: a, ventral view; 6, internal view.
For abbreviations, see figure 85.
that the lengthening of the posterior process continues
to physical maturity. Enlargement of the posterior process
seemingly cannot be attributed to old age. One physically
immature individual (USNM 23203) has the posterior
process (length, 90 mm.) unusually expanded toward its
distal extremity (greatest diameter, 77 mm.). Epiphyses are
ankylosed to the centra of only 3 of the 36 vertebrae
associated with this specimen. Continued growth of the
anterior process appears somewhat limited.
The anterior process (pro-otic) is very short, dorsoven-
rally compressed distally; the labyrinthic region is enlarged,
bulbous, and sculptured (fig. 87a). The relatively short
anterior process and the adjoining labyrinthic region are
securely lodged in an excavation on the cerebral face of
the squamosal. The thin anterior pedicle (fig. 87a) of the
tympanic bulla is fused with the epitympanic face of
the anterior process in front of the fossa for reception of the
head of the malleus. This shallow concavity for the head of
the malleus is located either anterior to or alongside
(USNM 23055) the epitympanic orifice of the Fallopian
aqueduct. Overhang of the obliquely inclined external face
of the pars cochlearis conceals the fenestra ovalis from a ventral
view.
On some periotics (USNM 22995) an anteroposterior
crease divides the external and internal portions of the
tympanic or ventral face of the pars cochlearis, the outer
portion being normally smooth and convex. On other
periotics the internal or cerebral portion of this ventral
surface is irregularly excavated or depressed (USNM 13874).
On most periotics the smooth convex ventral surface of the
tympanic face of the pars cochlearis does not extend inward as
far as the rim of the internal acoustic meatus.
The small fossa for the stapedial muscle is slightly rugose
and extends downward on the internal face of the base of
the posterior process and on the external face of the pars
cochlearts. On some periotics (USNM 22995) the functioning
of the muscle attached in this fossa would appear to have
been considerably restricted by the extent of the projecting
ledge above the fenestra rotunda.
Measurements (in mm.) of the periotics are as follows:
USNM USNM USNM USNM MHNB1
10668 13874 22995 16119 29
Right Right Right Right Right
Length of posterior process, 48 66 83 87 122
distance from external wall
of stapedial fossa to
extremity
Greatest dorsoventral depth 43 43 53 52
of periotic (from most
inflated portion of
tympanic face of pars
cochlearis to most projecting
point on dorsal face
Distance between 30 33 44 4]
epitympanic orifice of
Fallopian aqueduct and
extremity of anterior
process
Distance from external end 82 O77 iis ite 166
of posterior process to
anterior end of anterior
process (in straight line)
53.6
BW 2
1 “Tdiocetus” laxatus Van Beneden, No. 29, Musée royal d’Histoire
naturelle de Belgique, Bruxelles.
188 UNITED STATES NATIONAL MUSEUM BULLETIN 247
Auditory Ossicles
Rather rare preservation of the auditory ossicles of Calvert
mysticetes seems attributable in part to the fragile nature
of the anterior and posterior pedicles that attach the tym-
panic bulla to the periotic. Tidal action, which periodically
washed skulls cast on the beach, probably resulted in break-
age except when favorable conditions lead to rapid burial,
in sediments. In a relatively few instances skulls have been
excavated that have the tympanic bulla crushed against the
periotics in approximate normal position. In other instances,
the tympanic bullae are found dislodged and shoved into
the tympanoperiotic recess of the cranium or occasionally
somewhere near the skull. The outer lip of the detached bulla
is often fractured and it usually lacks both the anterior and
posterior pedicles. Quite frequently the labyrinthic region
of the periotic is broken off at the point of connection with
its posterior process (opisthotic). All of these hazards of pres-
ervation have limited the possible recovery of the auditory
ossicles.
Of the 34 Calvert tympanic bullae in the collection only
one (USNM 15576) retained the malleus attached to the
outer lip. A detached malleus was found in the matrix con-
tained in the epitympanic cavity of one periotic (USNM
23015).
PART 8
The slender stalklike processus anterior (Ridewood, 1922,
pp. 241, 247) of the malleus is ankylosed at the base with
the outer lip of the bulla (fig. 85a) along the anterior border
of the sigmoid process (USNM 15576). The two facets on
the head of the malleus that articulate with the incus have
the same shape and relationship as the corresponding facets
of Balaenoptera borealis.
The nearly vertical dorsal hemicircular facet meets the
smaller horizontal facet at a right angle, and both facets are
situated above the internal dorsal face of the prominent
tubercle. At the internal end of the tubercle (processus
muscularis) the short manubrium is more acuminate and
less nipple-like and not as noticeably bent backward at its
distal extremity as the corresponding process of B. borealis,
although the scar for attachment of the ligamentary process
of the tympanic membrane is likewise located ventrally at
the distal end. A similar attachment has been reported for
Balaenoptera musculus by Lillie (1910, p. 779). On each of the
two small circular nodules on the anterior face of the head
of the malleus there is a scar. To the scar on the nodule
located anteriorly on the rounded tubercle of the head of the
malleus the tensor tympani tendon was attached (Doran,
1878, p. 454). The scar on the adjacent nodule located
anteriorly on the outer portion of the head of the malleus
presumably served for attachment of a little ligament.
Ficure 89.—Views of right and left mandibles, USNM 10677, of Partetobalaena palmeri Kellogg: a, dorsal view of left mandible; 6, external
view of right mandible; c, dorsal view of right mandible. Abbrs.: an., angle; cm., condyle of mandible; cor., coronoid process; f.g.,
gingival or alveolar foramen; f.m., mental foramen; ipt., groove for attachment of internal pterygoid muscle.
PARIETOBALAENA PALMERI 189
Ficure 90.—Views of right mandible, USNM 11535, of Parietobalaena palmeri Kellogg; a, external view; b,dorsalview. For abbreviations,
see figure 89.
These two small nodules are also located in the same relative
position on the malleus of B. borealis. The head of the malleus
measures 1] mm. in length and 7.2 mm. in width.
No incus was found associated with the ear bones of the
Calvert cetotheres collected for the vertebrate paleonto-
logical collections. Quite probably this little ossicle may
have been overlooked in some instances when the tympanic
bulla or periotic have been freed from the enveloping matrix.
On all periotics of this species examined the stapes had
been dislodged and lost.
Mandibles
Both mandibles (fig. 89a-c were associated with one
(USNM 10677) of the four more or less complete skulls
(USNM 16570, 23022, 23725), but none were found near
the type cranium (USNM 10668) that belonged to a rather
young individual. A longer right mandible (USNM 11535),
which was intermingled with a number of skeletal elements
including a cranium, rostral bones, bullae, periotics, seven
vertebrae, ribs, and a humerus, is essentially complete
except for limited erosion of the articular face of the
condyle. This individual was not physically mature, since
the epiphyses were not ankylosed to the centra of the
cervical vertebrae. Less complete mandibles provided
supplementary information. One of the smallest (fig. 91 a, b)
is a left mandible (USNM 12697; length 918 mm.,
anterior end missing) of a young whale about the same age
as the type, whose greatest vertical diameter anteriorly is
58.5 mm.
When compared with the mandibles of the Belgian
Anversian fossil mysticetes described by Van Beneden,
the resemblances shown by the mandible of Isocetus depauwit
to the Calvert mandible require more than a cursory
assessment. The length in a straight line of the type left
mandible of J. depauwit (MHNB 170; Van Beneden, 1886,
pl. 70, fig. 1) is 1128 mm. and that ofa Calvertright mandible
(USNM 11535; fig. 90 a, b) is 1195 mm. The vertical
diameter of the mandibular ramus of this Belgian species
near the distal end is 84 mm., and the same measurements
for this Calvert mandible is 73 mm. The Belgian mandible
is thus slightly shorter but more robust than that of the
Calvert cetothere.
The profile of the articular face of the condyle of the
Calvert mandible compares favorably with that of I. depauwiz
(Van Beneden, 1886, pl. 70, fig. 8), which measures 55
mm. transversely. The greatest transverse diameter of the
condyle of these small Calvert mandibles ranges from 55
mm. (USNM 11535) to 62 mm. (USNM 23203) and 80
mm. (USNM 23731). Increase in width certainly modifies
the profile of the condyle (fig. 92a—c) and this fact leads
clearly to the inference that unlimited reliance should not
be placed on the condyle for defining mysticete genera, at
least for related genera. More weight should be accorded
to the sum or combination of less variable diagnostic
characters.
During growth toward physical maturity, a widening of
the mandibular condyle and its covering fibrous pad for
the usual attachment to the glenoid articular area would
accompany an increase in width of the postglenoid process.
The maximum side to side expansion of the condyle may
occur either above (USNM 23731) or below (USNM 7424)
the middle of its vertical diameter. The articular surface
190
UNITED STATES NATIONAL MUSEUM BULLETIN 247
— =.
== SSS ———
Ficure 91.—Views of left mandible, USNM 12697, of Parietobalaena palmeri Kellogg, young individual: a, external view;
b, dorsal view. For abbreviations, see figure 89.
of the condyle may be either somewhat flattened (USNM
23731) or convex (USNM 23203). On all the mandibles
the condyle is bounded ventrally on the internal face of
the ramus above the angle by the deep groove for the
attachment of the internal pterygoid muscle. This groove
is not extended across the posterior articular surface.
With one exception the dorsal portion of the condyle is
bent inward to conform with the curvature of the rim of
the ramus behind the coronoid process; on this mandible
(USNM 23203; fig. 92c) the rim is abnormally abruptly
depressed some 20 mm. below the forward projecting
dorsal edge of the condyle. On other mandibles, the
forward curving external border of the condyle projects
noticeably beyond the lateral surfaces of the adjacent
ipt.
C
Ficure 92.—Posterior views of condyles of mandibles of Parieto-
balaena palmeri Kellogg: a, right mandible (USNM 7424); 6,
right mandible (USNM 23731); c, right mandible (USNM
23203). For abbreviations, see figure 89.
portions of the ramus. Lengthening of the mandibular
ramus is accompanied by an increase in the interval
between the condyle and the coronoid process. On three
of the mandibles, the posterior articular surface of the
condyle is, respectively, 150 mm. (USNM 23203), 180 mm.
(USNM 11535), and 200 mm. (USNM 7424) distant from
the center of the apex of the coronoid process.
The coronoid process (fig. 90b) is bent outward and less
noticeably backward above and anterior to the entrance
of the mandibular canal, terminating in an everted apex,
convex internally and concave externally. For a distance
of 650 mm. in front of the apex of the coronoid process a
groove or rather a longitudinal ridge (fig. 90b) forms the
dorsal edge of the horizontal ramus. The small internal
nutritive foramina make their appearance posteriorly about
75 mm. anterior to the apex of the coronoid process and
below its rising anterior rim; commencing at a level about
10 mm. below the dorsal edge of this rim they rise gradually
to the dorsal surface anteriorly. At the anterior end of this
ridge these small internal foramina and their anteriorly
directed narrow grooves follow the dorsal surface to the
extremity of the horizontal ramus, the terminal groove
being more than 100 mm. in length. There are at least 20
of these small internal nutrient foramina on the right
mandible (USNM 11535).
The most posterior mental foramen (fig. 90a) on the
external surface of the right mandible (USNM 11535) is
located 410 mm. anterior to the posterior articular face
of the condyle. There are eight mental foramina on this
PARIETOBALAENA PALMERI 191
mandible, each opening into an anteriorly directed groove
of variable length (15 to 80 mm.). Eight mental foramina
(fig. 89b) are present on both of the shorter mandibles
(USNM 10677). A large terminal foramen (fig. 89a) is
present below the dorsal edge at the end of the mandible.
Spacing of the external mental foramina varies from 38 to
88 mm. on one mandible (USNM 11535), 60 to 117 mm.
on another (USNM 13903), and 76 to 97 mm. on a third
(USNM 10677). Similar variation in spacing is exhibited
by the internal nutritive foramina.
Behind the distal one sixth (200 mm.) the lateral surfaces
(fig. 93) of the mandibular ramus become progressively
more convex dorsoventrally, the external more especially
so than the internal surface. The convex curvature of the
external surface ends abruptly where it meets at an acute
angle (fig. 93e) the ventral limit of the internal surface.
All mandibles referred to this species are bowed outward.
Viewed from the side, the ventral profile of the mandible
is almost straight. The symphysis was short. Above the
ventral edge of the anterior one ninth of the horizontal
ramus and below the short longitudinal crease, the lower
border (dorsoventral depth, 20 mm.) of the internal face
of the ramus is depressed.
VUDOC
Ficure 93.—Cross sections of right mandible, USNM 11535, of
Parietobalaena palmert Kellogg: a, 100 mm. behind anterior end;
6, 300 mm. behind anterior end; c, 500 mm. behind anterior
end; d, 700 mm. behind anterior end; e, 900 mm. behind anterior
end.
The mandible being comprised internally to a varying
extent of porous bone, depending in part on age and
growth factors, and saturated in Recent mysticetes with
oil, is susceptible to alteration and compression by the
crushing effects of weight of overlying sediments. Allowance
accordingly should be made for distortion in comparative
measurements of the mandibles.
Measurements (in mm.) of the mandibles are as follows:
USNM USNM USNM
11535 10903 10677
Right Left Left
Greatest length of mandible as 1195 1164 983
preserved in a straight line
Greatest length of mandible as 1230 1200+ 1046
preserved along outside curvature
USNM USNM USNM
11535 10903 10677
Right Left Left
Distance from anterior end to level 1035 1041 937+
of center of apex of coronoid
process along outside curvature
Greatest vertical diameter 100 mm. 13 70.5 78.2
behind anterior end of ramus
Greatest transverse diameter 100 30.5 29 325
mm. behind anterior end of ramus
Greatest vertical diameter 300 mm. 63.5 64.5 66
behind anterior end of ramus
Greatest transverse diameter 300 42.5 37.5 44.2
mm. behind anterior end of ramus
Greatest vertical diameter 500 mm. 67 64.5 69
behind anterior end of ramus
Greatest transverse diameter 500 48 43.7 46.2
mm. behind anterior end of ramus
Greatest vertical diameter 700 mm. 66.7 64.7 63.6
behind anterior end of ramus
Greatest transverse diameter 700 52 45.5 49.5
mim. behind anterior end of ramus
Least vertical diameter of ramus 80 74 —
between coronoid process and
condyle
Greatest vertical diameter through 116 98 128 +
coronoid process
Greatest vertical diameter of hinder 102 — —
end of ramus including condyle
Greatest transverse diameter of 55 — —
condyle
Vertebrae
Thirty eight vertebrae (USNM 23203), including 7 cer-
vicals, 12 dorsals, 10 lumbars, and 9 caudals of | skeleton,
and 4 dorsals (USNM 23448) of another individual are
referred to this species. The epiphyses of most of the verte-
brae belonging to the first mentioned skeleton are detached,
an indication of physical immaturity. The 4 dorsals, how-
ever, have all epiphyses firmly ankylosed and are obviously
physically mature; their dimensions and structural features
closely parallel those of the longer series. The measurements
suggest that the 12 dorsals and the 10 lumbars are a con-
secutive series. Twelve dorsals and 1] or 12 lumbars were
present in the vertebral column of the larger Calvert
cetotheres.
The total length of the skeleton, including the skull
(length, 1115 to 1250 mm.), from the extremity of the
rostrum to and including the terminal caudal did not
exceed 14 or 15 feet.
CERVICAL VERTEBRAE.—None of the cervical vertebrae
(USNM 23203) were ankylosed to either the one in front
or the one behind. All have the epiphyses detached from
192 UNITED STATES NATIONAL MUSEUM BULLETIN 247
the centrum. The atlas has a vestigal ridge-like neural
spine, and short, thick, and blunt transverse processes. The
hyapophysial process, if present on the narrow splintered
ventral strip, was reduced to a thin backward projecting
shelf.
The roof of the axis is concave ventrally and ornamented
dorsally with 3 thin longitudinal ridges, widened and
truncated posteriorly, and deeply excavated anteriorly.
The axis has a small obtuse odontoid process; the transverse
processes are broad at the base, tapered toward their
extremity, turned downward and backward, and imper-
forate. An irregular depression at base posteriorly on
each process marks the former location of the foramen
transversarium. Upper and lower transverse processes of
the third cervical are not united distally by an osseous
isthmus to enclose the cervical extension of the thoracic
retia mirabilia; the slender attenuated lower process is
Ficure 94.—Anterior view of atlas, USNM 11535, of Parieto-
balaena palmeri Kellogg. Abbr.: tr., transverse process.
bent more backward than downward. Extremities of
upper and lower transverse processes of the fourth cervical
are broken off and missing; the lower process is dorso-
ventrally compressed near its base, directed downward
and slightly backward. Upper transverse process of fifth
cervical is anteroposteriorly compressed near the base,
attenuated distally; the lower transverse process is slender,
bent more backward than downward; extremities of these
processes are broken off and missing. All processes of the
sixth cervical are broken off near the base; slender lower
transverse processes were present; the anteroposteriorly com-
pressed upper transverse processes were rather broad at
the base. The seventh cervical lacks lower transverse pro-
cesses; the anteroposteriorly compressed upper transverse
process is broad at the base.
Viewed from in front the profile of the centrum of the
sixth and seventh cervicals is elliptical, the vertical diameter
PART 8
Ficure 95.—Anterior view of third cervical vertebra, USNM
11535, of Parietobalaena palmeri Kellogg. Abbrs.: d.a., diapo-
physis; p.a., parapophysis.
of the fifth (63 mm.) exceeds that of the preceding cervicals,
and the fourth and third were widened transversely.
The length of the 7 cervical vertebrae, including the
cartilaginous intervertebral disks, is approximately 235 mm.
(9¥ inches).
The distance (124 mm.) between the outer edges of the
anterior articular facets of the atlas (fig. 94) of another
physically immature specimen (USNM 11535) is less and
rr e
7 ff. sok (ni ii whet
“4 ¢ “sh mi lipte sit
te
a.
Ds We
Ficure 96.—Anterior view of fourth cervical vertebra, USNM
11535, of Parietobalaena palmeri Kellogg. For abbreviations,
see figure 95.
PARIETOBALAENA PALMERI
193
USNM 23203-Cervical Vertebrae
Greatest vertical diameter of vtebra, tip of neural spine to ventral
face of centrum
Greatest anteroposterior diameter of centrum
Greatest vertical diameter of centrum, anteriorly
Greatest vertical diameter or neural canal, anteriorly
Greatest transverse diameter of neural canal, anteriorly
Greatest distance between outer ends of parapophyses
Least anteroposterior diameter of right pedicle of neural arch
Greatest distance between outer magins of anterior articular facets
Vertical diameter of anterior articular surface
Greatest vertical diameter of centrum, posteriorly
Greatest transverse diameter of centrum, posteriorly
Atlas Axis C.3 C.4 C.5 C.6 G7
104 = = = = = —
58 50P Apo Bo SOS Zoe 26>
= = 65 59 64 62 56
64 = = a ia = —
44 47.5 = = = = =
150 192 = = = = —
— = 10 10.5 11 10.5 12
S29) = =
85 U2 = = = = —
45 54 65 60 62 58 57.5
131 94 77 87 76 77 78
a= Anterior epiphysis missing. b>—Both epiphyses missing. Posterior epiphysis missing.
the centrum is much thinner (43 mm.) than USNM 23203.
This atlas also lacks a neural spine and the shape of the
transverse processes is similar. Four additional cervical ver-
tebrae were associated with this specimen. The anterior
profile of the centra of these cervicals is more rectangular
and thus differs from the elliptical shape of USNM 23203.
On the third cervical (fig. 95) the lower transverse process
is directed outward, widened at the extremity and not bent
backward; the basal portion of the combined pedicle of
the neural arch and the diapophysis is narrow, noticeably
less widened than on USNM 23203. The transverse pro-
cesses of the fourth cervical (fig. 96) are slender and the
upper process is not expanded dorsoventrally. Very slender
upper and lower transverse processes are present on the
fifth cervical (fig. 97); the neural spine on the complete
neural arch is very short; and the centrum is quite thin
(19 mm.). The centrum of the sixth cervical (fig. 98) is as
AMAR Mss
it ete
WO he oe
Wt GUL Laren)
Nuc eer
N) | yes S}iulnis
Whi a rin ayy
HE ONS
ce =
I
t
Ficure 97.—Anterior view of fifth cervical vertebra, USNM
11535, of Parietobalaena palmeri Kellogg. For abbreviations,
see figure 95.
= rte ah ee
AV\e Uy 8S ye
Naa)
Ficure 98.—Anterior view of sixth cervical vertebra, USNM
11535, of Partetobalaena palmeri Kellogg. For abbreviations,
see figure 95.
thin as the fifth; the dorsovental diameter (18 mm.) of the
combined basal portion of the pedicle of the neural arch
and diapophysis is less than half the corresponding measure-
ment (39 mm.) of USNM 23203. Growth and individual
variability of the cervical vertebrae tend to minimize the
accuracy of any identification of nonassociated specimens.
Although the atlas is the most variable of the cervical verte-
brae, the inclosure of the cervical extension of the thoracic
retia mirabilia seems not to have resulted in any uniform
modification of the upper and lower transverse processes.
Measurements (in mm.) of cervical vertebrae, USNM
23203, are as indicated above.
DorsAL VERTEBRAE.—Both epiphyses are detached from
the centra of the 12 consecutive dorsals (USNM 23203)
All of the epiphyses are, however, firmly ankylosed to the
194 UNITED STATES NATIONAL MUSEUM BULLETIN 247 PART 8
USNM-23208 Dorsal Vertebrae
D.2 D3 D4 D5 D6 Di D8. DIST D10 Depa
Anteroposterior diameter of centrum 33D 438 HOP” 47550 s ose 64> 625 79 789 76» 85P
Transverse diameter of centrum anteriorly 82 84 76 78 81 81 83 74 73 77 69
Vertical diameter of centrum anteriorly 53 52 54 54 54 63 59 62 59 63 63
Tip of neural spine to ventral face of = 160 = = == = = WARP Ue —
cantrum posteriorly
Minimum anteroposterior length of 16 19.5 20 2710 34 42 50 46 51 52 50
pedicle of neural arch
Transverse diameter of neural canal 47 43 43 45 40 43 42 31 29 31 28
anteriorly
Vertical diameter of neural canal anteriorly _ 31 a = = = = 28 30 30 27
Distance between ends of transverse 193 181 166 — 146.5 148 158+ 170 208 230+ 231+
processes
Dorsal edge of metapophysis to ventral — 68 66 — 77.5 + — —— 100 ats 111
face of centrum anteriorly
Transverse diameter of centrum posteriorly 86.59! 76at B9at goat 90 of 87-8 77. 76 79 78 79
Vertical diameter of centrum posteriorly Bae 53 53 54 56 59 59 59 62 65 64
8— Anterior epiphysis missing. | »>=Both epiphysis missing.
centra of the 4 dorsals of another individual (USNM
23448). The anteroposterior diameters of the centra of
the dorsals increase from the first to the twelfth and the
transverse diameter of each exceeds the vertical diameter of
the anterior end. From before backwards, the profiles of
both ends of consecutive dorsal centra are modified from
a dorsally flattened and transversely widened ellipse on
the anterior dorsals to a more definite subcordate shape
from the middle to the posterior end of this series.
On each side of the centrum of the first to seventh dorsals,
inclusive, below the level of the floor of the neural canal
and adjacent to or on the edge of the posterior epiphysis,
there is an articular facet for the capitulum of the following
rib. No vestige of this facet can be recognized on the eighth
dorsal. The transverse diameter of the neural canal of the
second dorsal (47 mm.) exceeds that of the twelfth (28
mm.); the vertical diameter of the neural canal is decreased
less noticeably.
The pedicles of the neural arch are robust and wide on the
anterior eight dorsals. The articular ends of the diapophyses
progressively increase in width from the first to the eighth
dorsal. On these eight anterior dorsals the diapophyses
arise in part from the pedicle of the neural arch and in
part from the dorsointernal portion of the centrum
anteriorly. The parapophyses of the ninth to twelfth dorsals,
inclusive, project outward from the lateral surface of the
centrum and progressively increase in length. These
processes are bent upward on the ninth, tenth, and eleventh
dorsals. The neural spines are incomplete on all the dorsals;
there is, however, a marked increase in the anteroposterior
diameter of the neural spine at the base toward the hinder
end of this series. The width of the interval between the
opposite prezygapophysial facets decreases from the
P= Posterior epiphysis missing.
at— Posterior demifacet present.
anterior to the posterior end of the dorsal series.
On the first six of the anterior dorsals, the articular facet
on each metapophysis is flat; the demarcation of the outer
edge of this facet by an anteroposterior crest becomes
prominent on the seventh and presumably also on the
eight, but certainly on the ninth this crestlike development
has culminated in the inclination of each metapophysis
to almost vertical. These side to side compressed meta-
pophyses increase in size and rise higher above the floor
of the neural canal from the eighth dorsal to the posterior-
most lumbar.
The total length of the twelve dorsals, including the
cartilaginous intervertebral disks, is about 760 mm. (30
inches).
Measurements (in mm.) of dorsal vertebrae, USNM
23203, are as indicated above.
Measurements (in mm.) of dorsal vertebrae, USNM
23448, are as follows:
D.2 D.5 D6 D.7
Anteroposterior diameter of centrum 36 51 56.4 61
Transverse diameter of centrum, 82.5 82 84 84
anteriorly
Vertical diameter of centrum, 54.5 54 58.5 59
anteriorly
Minimum anteroposterior length of 13 25) 72a 41
pedicle of neural arch
Transverse diameter of neural canal, 52 50 49 47
anteriorly
Vertical diameter of neural canal, 27 29) 22) 20
anteriorly
Distance between ends of 181 159 151 150
diapophyses
Dorsal edge of metapophysis to 72 71 74 80
ventral face of centrum anteriorly
PARIETOBALAENA PALMERI
D.2 D.5 D.6 D7
Tip of neural spine to ventral face 112 134 167 184
of centrum posteriorly
Transverse diameter of centrum 86 93 95 95
posteriorly, including demifacets
Vertical diameter of centrum 55 54 57 61
posteriorly
Distance between outer margins of 81 68 65 54
prezygapophysial facets
Distance between outer margins of 70 49 26 24
postzygapophysial facets
LUMBAR VERTEBRAE.—When excavated the epiphyses of
the 6 anterior lumbars (USNM 23203) were detached; both
epiphyses were attached to the centra of the seventh and
eighth lumbars; and the anterior epiphysis was ankylosed
to the centrum of the ninth and tenth lumbar. Four of the
lumbars lack most of the neural arch, the neural spines of
all the lumbars are either damaged, incomplete or missing;
the first, second, fifth, and ninth lumbars possess an essen-
tially complete left transverse process; and the metapophyses
are preserved on the first and ninth lumbars, but are missing
of the others.
A rather sharp-edged ventral median longitudinal keel is
developed on the centra of the second to tenth lumbars,
inclusive; no rudiment of this keel, however, is present on
the first lumbar. In serial sequence, the centra increase in
length from the first to the posteriormost lumbar, the trans-
verse and vertical diameters of the neural canal diminish,
and the transverse processes are shortened. The transverse
processes of the first, second and fifth lumbars are slender,
elongated and are directed slightly forward. As compared
to the first and second lumbar, the left transverse process
on the ninth lumbar is broader (minimum anteroposterior
diameter, 45 mm.), shorter, and is directed more obliquely
forward. The elongated thin lamina-like metapophyses pro-
ject upward and forward beyond the level of the anterior
face of the centrum and are inclined obliquely outward
from ventral to dorsal edges. The neural spine of the ninth
USNM 23203—Lumbar Vertebrae
Anteroposterior diameter of centrum
Transverse diameter of centrum anteriorly
Vertical diameter of centrum anteriorly
Minimum anteroposterior length of pedicle of neural arch
Transverse diameter of neural canal anteriorly
Vertical diameter of neural canal anteriorly
Distance between ends of transverse processes
Dorsal edge of metapophysis to ventral face of centrum anteriorly
Transverse diameter of centrum posteriorly
Vertical diameter of centrum posteriorly
b—Both epiphyses missing. —»Posterior epiphysis missing.
275-699—68——_7
195
lumbar was more strongly inclined backward than that of
the first lumbar. Assuming that at least 11 vertebrae com-
prised the lumbar series, the estimated length of this section
of the vertebral column is 1125 mm. (44% inches).
Measurements (in mm.) of lumbar vertebrae, USNM
23203, are as indicated below.
CAUDAL VERTEBRAE.—Of the 9 caudal vertebrae (USNM
23203), the first to the sixth, inclusive, are consecutive;
the remaining three are regarded as the ninth, tenth, and
twelfth. The epiphyses were associated with but not at-
tached to the centra or the first and second caudals. Eleven
caudals (USNM 16667) of another individual are con-
secutive from the fourth to the fourteenth, the terminal
vertebra. The epiphyses of the fourth and fifth caudals
of this series were not ankylosed to the centra, but are
firmly attached on the others. Associated with these caudals
were 1 dorsal and 2 lumbars that lack epiphyses; this
individual was not only smaller but also less mature than
USNM 23203.
The anteroposterior, as well as the transverse and vertical
diameters of the anterior end of the centrum, diminish
from the first to the terminal caudal; the reduction of these
dimensions is rather abrupt behind the tenth caudal.
These four or five terminal caudals are embedded in the
caudal flukes of Recent mysticetes. The interval between
the dorsal edges of the opposite metapophyses progressively
diminishes from the first to the sixth caudal; these processes
are strongly reduced, almost vestigial on the seventh and
eighth caudal. On the five anterior caudals, these meta-
pophyses are curved upward and outward.
The neural spines of the 3 anterior caudals, although
relatively short, project above the metapophyses; they
diminish rapidly in height behind the first caudal and on
the fifth to the eighth, inclusive, are reduced to a low crest.
The neural canal, which has a roof as far backward as the
eighth or ninth caudal, decreases in transverse and vertical
diameter.
LEM AGE AGB MAGEE VILGD ST HOO IO AGS NED ESO
83> 81> 91 95.5 99 102 103 108 97° 101
72.5 71.5 68.5 65 73 74 76 79 75 85
63 66.5 63 67.5 66 70 72 #75 73° «75
41 — — —_— 47 — 46 45 4 —
28 — — — _— 23 19 13.5 NG Nee
30 —_— = — 35 —_— 28 24 19 —
—_— — — —_— 289 —_— _- — _-_ —
110 — — — — —_— — 133 = =>
79 74 71 74 75 75 77 +78 80 86.5
63 66 65 69 68.5 69 73° 75 G78)
196 UNITED STATES NATIONAL MUSEUM BULLETIN 247 PART 8
Measurements (in mm.) of caudal vertebrae, USNM 23203 and USNM 16667, are as follows:
USNM 23203-Caudal Vertebrae Cal Ga.2 Ga3 Ga.4(Ca.5 Ca:6\'Ga.9 Ca.10 Ca.12
Anteroposterior diameter of centrum 97° 108 108 106 103 85 > aOo 56.4 35
Transverse diameter of centrum anteriorly 83 83.5 82 81 87 89 74.5 67.5 46
Vertical diameter of centrum anteriorly 81.5 81.5 86 sii Sl Claes} 7A) TSM 41
Tip of neural spine to ventral face of centrum posteriorly 1525- 15s) eal 30 123 110+ 102 — — —
Minimum anteroposterior length of pedicle of neural arch 45 43 46 48 45 54 L5¥5 = =
Transverse diameter of neural canal anteriorly 16 14 14 WG 12 14 10 —_— ——
Vertical diameter of neural canal anteriorly 16 16 9 10 9 5 — — —
Distance between ends of transverse processes — 125-- 158-- — 123 104 — _— —
Dorsal edge of metapophysis to ventral face of centrum anteriorly 127 136 132 131 126 Qi — — —
Transverse diameter of centrum posteriorly = 81 87 86 86 = 70 63 43
Vertical diameter of centrum posteriorly = 88 105 100 86+ 89 74 65.5 35
USNM 16667—Caudal Vertebrae Ca.4 Ca.5 Ca.6 Ca.7 Ca.8 Ca.9 Ca.l0 Ca.11 Ca.12 Ca.13 Ca.l4
Anteroposterior diameter of centrum 93 77+ ® 86 83 78 68 51 Ship 29> 22» 19
Transverse diameter of centrum anteriorly 84 84 81 82 82 70 62 60 51 44 38
Vertical diameter of centrum anteriorly 83.5 84 85 a) i 74 64 50 42 35 32
Minimum anteroposterior length of pedicle of
neural arch 41.5 42 43 47 51 _ _— —_ —_— — —
Transverse diameter of neural canal anteriorly 20 17 13 es il 7 —_ — — — —
Vertical diameter of neural canal anteriorly 18 17 7 8 8 _— — — — — —
Distance between ends of transverse processes 148+ 127 110 94 — — _— _— — — —
Dorsal edge of metapophysis to ventral face of
centrum anteriorly, including haemapo-
physes Mies), WO JKOs 102 91 79 - — _— — —
Tip of neural spine to ventral face of centrum
posteriorly, including haemapophyses 127 Sells eos 104 94 — — — —_ _— —
Transverse diameter of centrum posteriorly 85 80.5 84 82) 73.9 65 55 50 46 —_ a
Vertical diameter of centrum posteriorly 85 82 83.5 80 76 69 57 48 41 _ _
«— Anterior epiphysis missing. = Both epiphyses missing.
The sharply defined median longitudinal ventral ridge
on the centrum of the posterior lumbar is replaced on the
first caudal (USNM 23203) by an anterior and posterior
low central protuberance, but no distinct tubercles. A
pair of large posterior haemal tubercles (hyapophyses)
are developed on the second and third caudals. An anterior
pair and a posterior pair of haemal tubercles are, however,
developed on the fourth and fifth caudals. On each side
of the haemal groove on these two caudals between the
anterior and posterior haemal tubercle is a notch through
which the segmented blood vessels pass on their upward
course on the lateral surface of the centrum in front of the
anterobasal angle of the transverse process and thence
obliquely to the posterior end of the neural canal.
Commencing with the sixth or seventh and present, as
well on the eighth, the anterior and posterior haemal
>= Posterior epiphysis missing.
tubercles on each side of the haemal groove are joined by
an osseous isthmus which is pierced by a foramen for
passage of the segmental blood vessels. The short transverse
process of these caudals is pierced centrally at the base by
a foramen for these blood vessels, which reach the posterior
end of the neural canal. The caudals behind the ninth,
the hindermost one to which chevrons were attached and
the last on which the roof of the neural canal persists, are
pierced by vertical passages from the ventral face to the
dorsal neural depression or groove. Three orifices on the
ventral surface and two on the dorsal surface of the cen-
trum provide the passage for branches of the caudal artery
and vein between the haemal groove and the terminal
portion of the neural canal.
The horizontally outward directed transverse process is
longer and narrower on the first than on the third caudal
which has the terminal portion widened; it is quite short
PARIETOBALAENA PALMERI 197
on the fifth, sixth, and seventh caudal. This process is the anteroposterior diameter of the centrum.
obliquely truncated distally on the seventh and is pierced The length of the fourteen caudal vertebrae, including
at the base by the vascular foramen. The transverse and __ the cartilaginous intervertebral disks, is about 1085 mm.
vertical diameter of the last five in the caudal series exceed (42%, inches).
BIBLIOGRAPHY
ABEL, OTHENIO
1938. Vorlaeufige Mitteilungen ueber die Revision der fossilen Mystacoceten aus dem Tertiaer
Belgiens. Bull. Mus. roy. d’Hist. nat. Belgique, Bruxelles, vol. 14, no. 1, pp. 1-34,
6 figs. February 1938.
Doran, ALBAN Henry GRIFFITHS
1878. Morphology of the mammalian ossicula auditus. Trans. Linnean Soc. London, ser. 2
(Zool.), vol. 1, pt. 7, pp. 371-497, pls. 58-64.
Litt, Dents GASCOIGNE
1910. Observations on the anatomy and general biology of some members of the larger
Cetacea. Proc. Zool. Soc. London, no. 51, pp. 769-792, figs. 69-78, pl. 74.
RmwEwoop, WALTER GEORGE
1922. Observations on the skull in foetal specimens of whales of the genera Megaptera and
Balaenoptera. Philos. ‘Trans. Roy. Soc. London, ser. B, vol. 211, pp. 209-272, 16 figs.
VAN BENEDEN, PIERRE JOSEPH
1886. Description des ossements fossiles des environs d’Anvers, Part 5: Cétacés. Genres:
Amphicetus, Heterocetus, Mesocetus, Idiocetus and Isocetus. Ann. Mus. roy. d’Hist. nat.
Belgique, Bruxelles, ser. Paléontologique, vol. 13, 139 pp., 75 pls.
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U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 46
LUMBAR AND CAUDAL VERTEBRAE, ANSP 12769, ESCHRICHTIUS PUSILLUS COPE (TYPE)
1, Dorsal view of lumbar; 2, lateral view of caudal; 3, dorsal view of dorsal vertebra.
DORSAL VERTEBRAE, ANSP 12769, MEGAPTERA EXPANSA COPE (TYPE)
4, Anterior view of eighth dorsal; 5, anterior view of fifth dorsal; 6, anterior view of ninth dorsal.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 47
DORSAL VERTEBRAE AND CONDYLE OF MANDIBLE OF MESOCETUS SIPHUNCULUS COPE
1, first dorsal, posterior view (AMNH 22669); 2, condyle of right mandible (AMNH 22665); 3, anterior dorsal, posterior view (AMNH
12669); 4, anterior dorsal, posterior view (AMNH 22669); 5, middle dorsal, anterior view AMNH 22669)
U.S. NATIONAL MUSEUM
RIGHT PERIOTIC AND AUDITORY
1, Incus with scar on crus longum and st
inte
LEFT PerRiotic, USNM
6, Cerebral or interna
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 49
SKULL, USNM 16783, DIOROCETUS HIATUS
1, Dorsal view; 2, ventral view.
BULLETIN 247, PLATE 50
U.S. NATIONAL MUSEUM
SKULL, USNM 23494, OF DIOROCETUS HIATUS
1, Dorsal view; 2, ventral view.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 51
RIGHT PERIOTICS
Aglaocetus patulus (USNM 13472): 1, ventral or tympanic view; 2, internal or cerebral view.
Diorocetus hiatus (USNM 23494): 3, internal or cerebral view; 4, ventral or tympanic view.
U.S. NATIONAL MuSEUM BULLETIN 247, PLATE 52
RIGHT SCAPULA AND RIGHT TYMPANIC BULLA, USNM 23494, DioROCETUS HIATUS
1, Internal view of right scapula. Right tympanic bulla: 2, dorsal view; 3, ventral view; 4, external view.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 53
CERVICAL AND DORSAL VERTEBRAE, AND ULNA, DIOROCETUS HIATUS
1, Anterior view of axis (USNM 16783); 2, anterior view of seventh cervical vertebra (USNM 23494); 3, anterior view of first dorsal
(USNM 16783); 4, internal view of left ulna (USNM 23494).
BULLETIN 247, PLATE 54
U.S. NATIONAL MUSEUM
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BULLETIN 247, PLATE 55
U.S. NATIONAL MUSEUM
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U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 56
VENTRAL VIEWS OF CAUDAL VERTEBRAE, USNM 16567, DIOROCETUS HIATUS
1, Second caudal; 2, third caudal; 3, fourth caudal; 4, fifth caudal; 5, sixth caudal; 6, seventh caudal; 7, eighth caudal; 8, ninth caudal;
9, eleventh caudal; 10, twelfth caudal; 11, thirteenth caudal.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 57
METAPODIALS AND CHEVRONS, USNM 23494, DIOROCETUS HIATUS
1, 2, 3, metapodials; 4, 5, phalages; 6, 7, lateral view of anterior chevron; 8, lateral view of first chevron; 9, 10, anterior view of anterior
chevron; 11, anterior view of first chevron.
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 58
DORSAL VIEW OF SKULL, USNM 23690, AGLAOCETUS PATULUS
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 59
VENTRAL VIEW OF SKULL, USNM 23690, AGLAOCETUS PATULUS
U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 60
LEFT PERIOTIC AND LEFT TYMPANIC BULLA, USNM 23690, AGLAOCETUS PATULUS
1, Tympanic or ventral view of left periotic; 2, cerebral or internal view of left periotic; 3, external view of left tympanic bulla; 4, ventral
view of left tympanic bulla; 5, dorsal view of left tympanic bulla.
BULLETIN 247, PLATE 61
U.S. NATIONAL MUSEUM
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U.S. NATIONAL MUSEUM
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U.S. NATIONAL MUSEUM BULLETIN 247, PLATE 66
DORSAL VIEW OF SKULL, USNM 16119, PARIETOBALAENA PALMERI
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BULLETIN 247, PLATE 67
VENTRAL VIEW OF SKULL, USNM 16119, PARIETOBALAENA PALMERI
Index
[Names of new genera and species in italics; page numbers of principal accounts in boldface.]
acutorostrata, Balaenoptera, 17, 40, 109,
110, 124, 160, 175
Aglaocetus, 163
moreni, 163
patulus, 163
agrami, Mesocetus, 118
alleni, Felsinotherium, 91, 92
Halitherium, 91
Amyda, 67
antillense, Halitherium, 66
antiquum, Halitherium, 91
antiquus, Crocodilus, 125
antwerpiensis, Thalassocetus, 51, 53, 59
Aphelops, 67
Archaeohippus, 67
Aulophyseter, 47, 55
morricei, 59
Balaena longimana, 116
novaeangliae, 116
palaeatlantica, 126
prisca, 1, 104, 116, 125
Balaenidae, 176
Balaenodon physaloides, 47
Balaenoptera, 103, 183
acutorostrata, 17, 40, 109, 110, 124,
160, 175
borealis, 103, 175, 189
musculus, 103, 175, 189
physalus, 103, 105, 106, 107, 109, 136,
175
prisca, 125
pusillus, 113
robusta, 104, 105
sursiplana, 104, 106, 107
Balaenopteridae, 3, 176
beaumonti, Metaxytherium, 69, 70
bill fish, 67
Bison, 91
borealis, Balaenoptera, 103, 175, 189
brevifrons, Cetotherium, 103
Heterocetus, 123
brialmontii, Plesiocetus, 104
brocchi, Cheirotherium, 68
buccatus, Tretulias, 104, 128
burtini, Plesiocetus, 103, 104
calvertense, Hadrodelphis, 99
Metaxytherium, 71
calvertensis, Pelocetus, 3, 112, 114, 120
capgrandi, Rytiodus, 78, 91, 92
Carcharhinus, 67
Carcharodon, 67
Caribosiren, 73
turneri, 66
Castoroides, 91
catodon, Physeter, 58, 61, 62
Cephalotropis, 2
cephalus, Cetotherium, 103
Eschrichtius, 1, 104, 105, 175
Cetotheriidae, 3
Cetotherium, 2, 103, 104, 133
cephalus, 105
dubium, 103
expansum, 117
expansus, 116
furlongi, 104
parvum, 114
priscum, 125
pusillum, 115
pusillus, 113
rathkii, 104, 123, 127, 128
Champsodelphis, 100
valenciennesii, 100
Cheirotherium brocchii, 68
Chelonia, 67
Choneziphius, 91
collinii, Halianassa, 69
cordieri, Metaxytherium, 70
crataegensis, Hesperosiren, 66, 77, 78, 84
crispatus, Syllomus, 118
cristolii, Halitherium, 69
crocodilinus, Orycterocetus, 48
Crocodilus antiquus, 125
cuvierii, Halicore, 70
Metaxytherium, 68, 70, 72, 73, 78, 80,
83, 84
Cynodon, 127
Cynorca, 67
Cyrtodelphis, 133
Delphinapterus tyrannus, 1, 2
Delphinodon, 67
depauwii, Isocetus, 119, 183, 189
Desmostylia, 65
Diaphorocetus, 47
poucheti, 49, 51, 52, 55, 61
Dioplodon, 91
Dioplotherium manigaulti, 91
Diorocetus, 134
hiatus, 134
Dorudon serratus, 91
dubia, Protosiren, 68, 69, 70
dubium, Cetotherium, 103
Halitherium, 70
dubius, Hippotamus, 68, 69, 70
Plesiocetus, 104
dugon, Dugong, 75
Dugong, 77
dugon, 75
Dugongidae, 65, 68
durinasus, Metopocetus, 1, 104, 121, 123,
124
Eboroziphius, 91
effodiens, Hemicaulodon, 65, 78
Elephas, 91
Eotheroides, 65
Equus, 91
Eschrichtidae, 3
Eschrichtius, 3, 104
cephalus, 1, 104, 105, 175
expansus, 116
glaucus, 175
leptocentrus, 1, 105
priscus, 125
pusillus, 1, 2, 104, 113
robustus, 115
Eubalaena glacialis, 175
Eurhinodelphis, 61, 67, 133
longirostris, 61
expansa, Megaptera, 1, 2, 104, 114, 116
expansum, Cetotherium, 117
expansus, Cetotherium, 116
Eschrichtius, 116
Siphonocetus, 116, 128
Felsinotherium, 68, 70, 72, 73, 85, 91
alleni, 91, 92
forestii, 68, 70
gastaldi, 93
ossivallense, 66, 68, 79
serresii, 68, 70, 73, 78, 82, 84, 88, 91, 93
floridanum, Metaxytherium, 79
forestii, Felsinotherium, 68, 70
furlongi, Cetotherium, 104
Galeocerdo, 67
garopii, Plesiocetus, 103, 104
gastaldi, Felsinotherium, 93
199
200 UNITED STATES NATIONAL MUSEUM BULLETIN 247
gervaisii, Plesiocetus, 103
giganteus, Manatus, 66
Trichecus, 66, 83
glacialis, Eubalaena, 175
glaucus, Eschrichtius, 175
Gomphotherium, 67
guicciardinii, Idiocetus, 133
guiscardii, Heterocetus, 134
Hadrodelphis, 99
calvertense, 99
hair seals, 67
Halianassa, 68
collinii, 69
studeri, 68, 69
vanderhoofi, 75, 77, 78
Halicore cuvierii, 70
Halitherium, 81, 85
alleni, 91
antillense, 66
antiquum, 91
cristolii, 69
dubium, 70
schinzi, 66, 68, 69, 76, 78, 81, 83, 84
serresii, 70
Hemicaulodon effodiens, 65, 78
Hemipristis, 67
Hesperhys, 67
Hesperosiren, 73, 85
crataegensis, 66, 77, 78
Herpetocetus, 133
Heterocetus, 123, 133, 134
brevifrons, 123
guiscardii, 134
Hexanchus, 67
hiatus, Diorocetus, 134
Hippopotamus dubius, 68, 69, 70
medius, 68, 69, 70
hupschii, Plesiocetus, 103, 104, 112
Hydrodamalis stelleri, 66
Idiocetus, 133, 134
guicciardinii, 133
laxatus, 123, 164, 187, 185
Idiophyseter merriami, 55
Idiorophus, 47, 55
Isocetus, 123, 133
depauwii, 119, 183, 189
Isurus, 67
jordani, Metaxytherium, 84, 92
kelloggi, Macrodelphinus, 100
kochi, Miosiren, 84
krahuletzi, Metaxytherium, 69, 83
laxatus, Idiocetus, 123, 164, 185, 187
leatherback turtle, 67
leptocentrus, Eschrichtius, 1, 105
Leptophoca, 67
longimana, Balaena, 116
longipinna, Megaptera, 116
longirostris, Eurhinodelphis, 61
Mesocetus, 2, 118, 122, 123
Lophocetus pappus, 100
Macrodelphinus kelloggi, 100
magdalensis, Potamosiren, 66
magnidens, Megalodelphis, 100
Manatus giganteus, 66
studeri, 68, 69
manigaulti, Dioplotherium, 91
Metaxytherium, 92
medium, Metaxytherium, 70, 78, 80, 84, 85,
86
medius, Hippopotamus, 68, 69, 70
Megalodelphis, 100
magnidens, 100
Megaptera, 37, 105, 116
expansa, 1, 2, 104, 114, 116
longipinna, 116
novaeangliae, 175
robusta, 104
Megatherium, 91
merriami, Idiophyseter, 55
Merychippus, 67
Mesocetus, 103, 118, 133
agrami, 118
longirostris, 2, 118, 122, 123, 124,
pinguis, 2, 117, 119, 129, 144, 145
siphunculus, 1, 104, 118
Metaxytherium, 68, 69, 70, 73, 85, 91, 92
beaumonti, 69, 70
calvertense, 71
cordieri, 70
cuvierii, 68, 70, 72, 73, 78, 80, 83, 84
floridanum, 79
jordani, 84, 92
krahuletzi, 69, 83
manigaulti, 92
medium, 70, 78, 79, 80, 84, 85, 86
ortegense, 93
vanderhoofi, 75, 77, 78
Metopocetus, 103, 121, 124
durinasus, 1, 104, 121, 123
vandelli, 123
Miosiren, 85
kochi, 84
moratus, Ulias, 1, 104, 129
morricei, Aulophyseter, 59
musculus, Balaenoptera, 103, 175, 189
Sibbaldus, 40
Mysticeti, 67
novaeangliae, Balaena, 116
Megaptera, 175
ortegense, Metaxytherium, 93
Orycterocetus, 47
crocodlinus, 48
quadratidens, 47, 48
ossivallense, Felsinotherium, 66, 68, 79
palaeatlantica, Balaena, 126
palmeri, Parietobalaena, 1, 104, 120, 133,
175, 176
pappus, Lophocetus, 100
Parietobalaena, 176
palmeri, 1, 104, 120, 133, 175, 176
parvum, Cetotherium, 114
patulus, Aglaocetus, 163
Pelocetus, 3
calvertensis, 3, 112, 114, 120
petersi, Thallatosiren, 78, 83
physaloides, Balaenodon, 47
physalus, Balaenoptera, 103, 105, 106,
107, 109, 136, 175
Physeter catodon, 58, 61, 62
Physeterula, 55, 61
dubusii, 59
pinguis, Mesocetus, 2, 117, 119, 129, 144,
145
Plesiocetus, 2, 103
brialmontii, 104
dubius, 104
garopii, 103
gervaisii, 103
hupschii, 103, 104, 112
Potamosiren magdalensis, 66
poucheti, Diaphorocetus, 49, 51, 52, 55, 61
prisca, Balaena, 1, 104, 116, 125
Balaenoptera, 125
| priscum, Cetotherium, 125
priscus, Eschrichtius, 125
Siphonocetus, 104, 125, 128
Procamelus, 91
Prorastomus, 65
sirenoides, 65
Proroziphius, 91
Protosiren, 65
dubia, 68, 69, 70
Psephophorus, 67
pusillum, Cetotherium, 115
pusillus, Balaenoptera, 113
Cetotherium, 113
Eschrichtius, 1, 2, 104, 113
Siphonocetus, 128
quadratidens, Orycterocetus, 47, 48
rathkii, Cetotherium, 104, 123, 127, 128
Rhachianectes, 3
Rhachianectidae, 3
Rhegnopsis, 2
robusta, Balaenoptera, 104, 105
Megaptera, 104
robustus, Eschrichtius, 115
Rytiodus capgrandi, 78, 91, 92
Scaldicetus, 55, 59, 61
caretti, 59
grandis, 59
schinzi, Halitherium, 65, 68, 69, 76, 78, 81,
83, 84
Schizodelphis, 133
scombroids, 67
senegalensis, Trichechus, 81
serratus, Dorudon, 91
serresii, Felsinotherium, 68, 70, 73, 78, 82,
84, 88, 91, 93
Halitherium, 70
sibbaldus musculus, 40
Siphonocetus, 2, 104, 125
expansus, 116, 128
priscus, 104, 125, 128
pusillus, 128
siphunculus, Mesocetus, 1, 104, 118
sirenoides, Prorastomus, 65
Squalodon, 67, 91, 133
stelleri, Hydrodamalis, 66
studeri, Halianassa, 68, 69
Manatus, 68, 69
sursiplana, Balaenoptera, 104, 106
Syllomus crispatus, 118
Taphrosphys, 67
Tapiravus, 67
Tapirus, 91
Testudo, 67
Thalassocetus, 61
antwerpiensis, 51, 53, 59
FOSSIL MARINE MAMMALS
Thallatosiren, 73
petersi, 78, 83
Thecachampsa, 67
Tomarctus, 67
Tretulias, 2, 128
buccatus, 104, 128
Trichechidae, 65
Trichechus, 66, 77
giganteus, 66, 83
senegalensis, 81
201
turneri, Caribosiren, 66
tyrannus, Delphinapterus, 1, 2
Ulias, 1, 129
moratus, 1, 104, 129
valenciennesii, Champsodelphis, 100
vandelli, Metopocetus, 123
vanderhoofi, Halianassa, 75, 77, 78
Metaxytherium, 75, 77, 78
Zarhachis, 67
U.S. GOVERNMENT PRINTING OFFICE: 1968
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